There are other glitches not exclusive to iOS that allow you to get more than 20 trinkets ;) It only makes a difference in the amount of trinkets displayed on the end game screen (and wherever else the trinket count is displayed).
Interesting find nonetheless, as your method is probably significantly faster for 105%.
Unfortunately, saving and quitting is banned in Any% no TJ, Any% no S+Q and 100%, so closing and reopening the app is not allowed in those categories...
The problem is that the game is not continuous, but divided into 1/30 second increments (or frames). That means sometimes you'll be 1 pixel away from the checkpoint on one frame, on the next frame you'll overlap with it by 9 pixels; other times you'll first be 9 pixels away, then overlap with it by 1 pixel. To activate the checkpoint, you have to have touched in on the previous frame. If you die on the same frame you touch it, it won't activate. So for some checkpoints you can go earlier, because the frames line up neatly, but for some checkpoints you'll have to go a bit later.
What decides whether or not it lines up well is which platform you fall / flip off of, so you should try to replicate exactly what the top runs do, because they (for the most part) line up the checkpoint deaths well. Also remember that the checkpoint deaths don't have to be frame perfect, even ones that don't die on the ceiling spikes still save time.
My best advice is to find visual cues (e.g. the moment a platform goes off screen) to time the input to drop onto the checkpoint. You'll have to experiment a bit, but it's not too hard to find relatively consistent visual cues.
PS: @Mindwaves each checkpoint death saves 0.7 seconds optimally, so the 6 checkpoint skips will usually save around 4 seconds in total.
The fastest setup method is to press up against the wall, tap left for one frame, then press left and flip at the same frame.
The route is simple enough, you can watch the record run and just follow along. The easiest way to do telejumps is by pressing Enter + R on the same frame (takes a couple tries at first), then holding right and mashing flip. This is somewhat consistent for some of the telejumps but two of them are a bit more precise. Pokecrafter64 made a short video explaining how to do them if you look in the guides. I recommend playing around with telejumps a bit, they take a little while to get used to.
I recommend playing on version 2.2 but 2.0 is also fine.
It's unlikely we'll add a separate leaderboard unless there are a large amount of runs done on the mobile version. However, everyone who runs this game seriously plays it on PC anyway, so there's no reason to add a mobile leaderboard.
Using a controller is allowed, because it doesn't give you an advantage over any other input method.
There's not a specific reason for it, but the reason Any% No Telejumping is run is because it's the "classic" VVVVVV speedrun. 100% No Telejumping would not be significantly harder than 100% with telejumps, only longer. The reason for this is that you can't "cheese" a level like you can with Warp Zone and Tower in Any%, because you still have to get the trinkets, so the only time you'd lose from skipping Telejumps is from walking to the level.
Generally in the speedrunning community, rebinding keys is allowed, but macros are not. You have to press every button yourself, so a macro to spam action would be forbidden.
Line skips save at most a few seconds, and even if you fail the line clip 4-5 times you only lose around a second, so it wouldn't save a lot of time anyway. In Any% there's only 4 useful line clips, so failing each one a few times would lose you only 4-5 seconds, so they're probably still worth attempting. If you can't get the clips consistently at all, consider just going around the line the standard way.
The way I do line clips is just to spam the space bar alternating with 2 fingers, which works quite well. If you really really want to get line clips first try every time, there's no other way than trying to time them, which is pretty hard. The inputs for that are to flip, wait 1 frame, then flip again. (So 2 flips with a 1/15th second pause.)
Also make sure to reset your save before attempting this, that can sometimes have an effect on the outcome.
It's a bit of an awkward telejump. The most reliable way to do it that I've found is to do the telejump, then wait for the second teleporter 'bang', then start spamming flip. It's important you're not moving, or it won't push you inside the wall.