Alright, let's get this out somewhere in order to document it. (Plus I'd rather not test all this myself).
Early game has several routing options that all converge at Main Reactor (DS1 room), some theoretical and some not. As I posted already, we can get an early Power Bomb when collecting Light Beam, which, in isolation, is most certainly faster than wallcrawling to the non-TAS option in Temple Grounds. But the catch is that it requires an Etank, which the only sensible option would be Mining Station Access. We do cross through this room inbounds in the route, since the Agon Temple SW is presumed faster than the Mining Plaza Sandigger SW. But in light of new tech (Extended Dash and Boost Boost), it's unclear how slow/fast these routes are compared to one another. The Power Bomb in Temple Grounds allows us to skip the Etank, and so that should be considered.
Next: Light Beam
after Dark Beam is extremely slow. People seem to not realize just how awful and indirect this path ends up being, because it's so standard, but if we look at Claris' GDQ run, the RTA from Dark Beam to collecting Light Beam is 2 minutes and 30 seconds. Of course there are cutscenes and non-TAS error, but this path involves considerable backtracking through the same rooms (between light and dark world), as well as a round-about path to the item itself. There are no SWs available to us in Dark Agon when entered from the Command Center portal which would allow us to wallcrawl to Light Beam, but there is potential if Dark Agon is entered through the Portal Terminal. A wallcrawl across Dark Agon could be used in place of the first wallcrawl to Main Reactor (Dark Beam) > enter dark world > travel in a large circle to Light Beam. And, it would also save even more time on the Power Bomb outside Light Beam, since you wouldn't need to reload the room to collect it. Since we enter Main Reactor again when leaving Light World, we could collect Dark Beam then. Crossroads should have a TAS viable SW, and, though it is similarly not exactly a 'nice and straight path', I believe it should be timed. (A more absurd potential would be to delay Light Beam until Dark Visor [...and SA and PBs] is/are obtained, which sounds unlikely but could potentially work out).
That early game stuff is tedious enough, but there's a much larger routing possibility looming over us. Light Suit is absolutely unneeded in a TAS setting and takes ridiculously long to acquire. With a combination of Screw Attack/Cannon Ball/Air Underwater (and TAS precision) all Sky Temple Keys which normally require Light Suit can be collected without it. It's even possible non-TAS with several Energy Tanks, but TAS will have no issue with much fewer. Obviously that actual number needs to be established. With this in mind, the main focus of early game should be to collect Screw Attack and Dark Visor as quickly as possible along with some etanks... Which is something I really don't want to outline every option for doing- there are too many, as well as more options could be made viable with some theoretical stuff.
(A part of me kind of wants the first TAS of this game to collect Light Suit and follow a more standard route, since it would give a valuable comparison for timing these more convoluted things, but I would be absolutely baffled if Light Suit could actually come anywhere near saving time).
Anyway, one last thing that will be useful for nearly any route: If someone can find a faster way from Lower Torvus to Upper Torvus without having already collected super missiles, that would be huge. Currently it seems all we can do is float up Cache B which probably takes at least half an hour if I had to ballpark it. I think even if Infinite Speed is required, it would still save time as long as the movement after the setup isn't excessively lengthy as well.
Edit: Well one of the theoretical things was solved
https://www.youtube.com/watch?v=cKG-RIIXvm0
