Also if you search “@threads.net” in your mastodon client and you find users from that server, then your server should be connected

Mh I don’t know. Guess it depends on the game then. I play most games with the touch pads. Just so much better if configured right. The touch pads can also be used for abilities or menus or inventory slots etc. It gives the steam deck so much versatility. You can play everything from a joystick only game To mouse dependent games to shooter.

Any heldhand without touch pads is basically useless, no? Why are they all going this route? Are those patented by valve or sth.?

In more general terms, you can look up the item at e.g. Idealo.de or other product comparison sites and then decide where to buy. Amazon is most often not the cheapest, even including additional delivery cost