I'll note that keyboard + controller IS legal for Emulator runs, and I think you can just have them both enabled at the same time. Probably doable with like the wermi fork of octomino plugin.
Carpetless is a pretty slow star all things considered. HMC Toxic Maze (even without BLJ), THI Reds, SL Reds, and TTM Monkey (barely) are all faster stars that you could add before Carpetless. Doing CCM 100c with Penguin Race and LLL 100c are also probably faster ways to get extra stars although I haven't done the calc.
Fun fact - in Parsee's 47:11 (right before he got WR in 70 star) he ran on JP instead of US (and in fact did not own a US cart iirc).
Also yeah right now there are no ideas for how to make 1 Key viable, and whenever I've asked the TASers they usually just say bluntly "it'll never happen", which at least goes to show their opinion of its difficulty. Carpetless was thought to maybe be possible for a long time, but it still took a decade for an idea to be turned into a working setup.
I'd like to note that that guy is definitely not the maker of the SM64 PC Port, literally just stole it and posted it on GameJolt, and doesn't even seem to realize why the game has an installer.
That being said, SM64 PC Port does have its own leaderboard. (Co-op and PC Port w/ Odyssey Moveset leaderboards also exist separately apparently).
You can easily get past the upstairs key door with LBLJ. But there's nothing there. To get upstairs you must activate the loading zone, and it can only be activated if Key 2 is in your inventory.
The vulnerability in PJ 64 can only happen if you load an unverified/unknown ROM. To prevent this, you can check the ROM hash to make sure it matches the real SM64 cartridge (differs for JP and US) (SM64 discord has a command w/ instructions for how to do that). tl;dr - for speedrunning doesn't matter unless you have a fake ROM.
Tbh there's probably no one making fake ROMs and distributing them. But if you want to be on the safe side, I would just avoid casual gaming on PJ 64 1.6
If you're asking why people submit Twitch VODs instead of another format - people are allowed to submit other formats. I submit my runs as YT videos. It's a matter of preference (although it is required that certain sites be used to prevent things like having videos suddenly become unavailable).
This category is just an inferior version of 10x DDD Skip. Something along these lines might exist on the Streaks spreadsheet though.
Edit: wait i realize you may be meme-ing on the other posts about a "10x" category.