Saw this post and figure out this is probably the best form of ipad mini for me to play PC game via steam link on bus: https://www.reddit.com/r/ipadmini/comments/v8t5th/ipad_mini_6_joycon_adapter/

I ordered the joy-con and installed iOS16 after this,
the pair of joy-con works well on apple game center games.

Sadly when I try them with steam link, steam link only can use one controller at a time in controller setting page. Although I can select both controllers and highlight them at the same time with long press of two fingers. Only still one controller is accepted when I connect the ipad to my PC.

I understand iOS16 just came out few weeks ago and joy con support was just added, it is quite rude to ask steam dev to accept joy con in such rush

Is there any quick fix or by pass for this? I just googled and found PC also have same issue and people need to install a thing called XInput to use joy con on PC for steam games.

I am finding a way to use XInput on iOS or something similar now, but any help will be nice, thanks a lot