I've beaten VNOG in less than an hour and a half. Could be shorter though if I could get better drops (i.e. Powerful Soul Stone from the first ape and all Great Masks from Burnaks).
There're no certain strategy in speedrunning VNOG other than planning in advance (e.g. get all the items in the village so you can start chapter 2 much faster and getting the Medium Ice Gears along the coast first) and having good luck at drops. It is also better to test a strategy with console commands before actually doing it. Writing down the steps helps out a lot.
The strategy that I use is to play as Hahli and defeat as many Water Burnaks (They are the easiest type of Burnaks that have a medium chance of dropping Great tier gears with high experience for early game; it is possible for Ice/Earth Burnaks to drop gears as well but they are usually of low quality) as possible to grind for Tier 3 gears at the beginning (WARNING: Involves high luck; Burnaks might not drop items) so you don't have to grind for shards or high experience for late game enemies. (The reason for choosing Hahli is as she already pocesses Water attack bonus, equipped with high tier Water gears her Elemental Special will be nigh unstoppable)
Once you get a set of Great Mask, Medium Armor and Heavy Greaves you are good to go up to the Virus Factory (afterwards you can obtain Heavy Armor at the area around Capes of No Hope). You don't have to hunt for gears of all elements, as the gears will boost all elemental stats. Just remember, you choose your gears with Tier as your highest pirority (as they mean more AP/MP/RP and more elemental stats boost) then Element (For Attack Gears you take the ones of your element; for Defense Gears you take the ones of your opposing element). However it doesn't matter much about the Elemental aspect of the gears as long as it is of a high tier as the MP/AP/RP are always worth more than Elemental Stats.
For all the optional enemies it is better to hide from them rather than confronting them, even if it means you don't move for a minute until they move aside to make a clear path for you. Trust me, it is often the better option to evade a long combat that you would likely lose or spend too much time on. If this fails, only engage them when they are grouped so you don't have to waste turns to chase them down. Defeat the Ganfa first as they always run away even if that means you have to suffer from other hard hitting attacks. Worse case scenario, you might just have to engage then abandon the fight, lose some experience and hope that they won't chase you again.
For combat just spam the Elemental Special to deduct enemies' AP so you don't have to suffer from damaging attacks and lose the fight. A deduction of 2AP can stop most enemies from attacking in the next turn, except for Piraka, Guard Burnak, certain Nektanns and Elite Ussal, but even so the AP deduction can prevent them from doing their most damaging attacks. This default attack is very useful as it consumes little AP and you can certainly immobilize at least one enemy in a turn once you get a Medium armor (Elemental Special costs 6AP, the Medium armor makes you own 12AP and 1 Elemental Special deducts 1-2AP). Standing in an corner to prevent attacks from all sides also helps, although this robs your mobility and at late game when enemies have high MP this won't work.
Also level up your Technique as it also allows more AP deduction (up to 2) per Elemental Special (also deals up to ~120 damage if w/ high tier gears + critical hit) and more chance for better Soul Stone/Life Stone heals, which is much better than Defense or Attack as the latter two can be acquired through gears. High Technique also allows you to completely nullify enemies' attacks by evasion, although you cannot evade stats deduffs.
As for the other weapons slots I prefer an enhanced Zamor Launcher so I can end a combat without moving much (also good for fighting Fikou/Rock Ussal/Ice enemies as they deduct your MP) and a Launcher so I can distance myself from powerful enemies; also these weapons are free in early mid-game if you know where to find them . They also consume medium AP so you can choose another attack in the same turn if you will and the best part is they both deal fairly high damage. Don't use melee weapons against Fikou/Rock Ussal/Ice enemies as they can immobilize you and you would waste a turn for nothing. Of course there's always the option of abandoning the battle, but the loss of experience can slow down progress. Also most importantly don't use weapons of your conflicting element as they will only deal minor damage.
Lastly, for the trinket slot I prefer either the (Powerful) Life Stone or Soul Stone. The standard versions of these trinkets are given to you by Garan as you progress, with the Life Stone available at early game. The Powerful version of the Life Stone can be found by defeating a certain amount of Master Nektanns (ensured drop but hard fights), while the Powerful Soul Stone is dropped rarely (by rarely, I mean a Makuta giving you a wholeheartedly friendly hug kind of rare) by The Stone Turtles or Lava Apes (easier fights but never seem to drop). They are both good healing items, but each have their own downsides. For example, Life Stone heals less than Soul Stone and uses 8AP making almost no other moves available, while Soul Stone only consumes 1AP but can only be used once. So choose carefully, whether you want to constantly heal or heal once in a battle.
EDIT: Glitch expliots
1. This one is more well known. If you click "Back To Home" instead of "Abandon Fight" you will quit a fight without losing experience and enemies will reset their location so you wouldn't easily get caught the second time.
2. If you run/walk past a Matoran before speaking to him/her you will make him repeat his/her last dialogue (Mostly the "I am busy; Come back later" one). This also updates the quest log so you can exploit this to save seconds from discussion by without having to click "Give items" or "So What's Next".
3. At one point you will have to escort a Matoran to the Capes of No Hope and then meet up with Garan. With a teleportation pack, you can engage at battle with an Ice Burnak at the end of the icy coast and teleport to the other side of the island so you can save a lot of trekking.