Rainbow six siege doesn't no, but pubg does on mobile.
https://www.youtube.com/watch?v=BTkAIbrENAE&ab_channel=Zendex
See attachment for M&K support via third party apps before Respawn tried their best to patch it after realising it was apart of native and players were taking advantage on PS4 by using third party apps so they weren't detected here.
This is Respawns official stance on M&K on consoles:
MOUSE & KEYBOARD USE ON CONSOLES
Our stance on this? The short answer is: we don't condone it. We are investigating ways to detect if players are doing it that we're testing internally. That's all we have to say on it for now but we'll revisit this and talk about progress with detection and how we'll address players that are using it in the near future.
And judging by Respawn banning players using M&K; I highly doubt they would decide to add support for M&K now. It would mean having to unban everyone who ever used a M&K.
Where are you getting your dates for M&K support from nothing other than guesstimating? A more accurate guesstimation date would be the 20th when the PS5 is released around the world, but, you know just as well as me all we got was "Coming in Fall".
The rule for online F2P is you follow the biggest titles on the market no matter your personal opinion
This isn't true, Apex went the complete other direction and they're doing well, they only started to copy Fortnites/Warzones after their ideas were stolen first, yet they still have unique ideas dropping every update. The first rule in business is to have a USP. Copying other F2P titles does nothing than make a clone, gives you no USP and makes you look like every other BR on the market. Above all, the game must also be fun else it will fail in all regards. Look at the battlefield that failed, it had so much promise, yet the lack updates and no USP in site destroyed it, despite being fun to play.