Adding workshop button for steam overlay that opens workshop for that title
Also
Family merging steam cloud via invite or link etc etc
Me and a family member are constantly google driving a game back and forth when our game both closed (steam remote play together but steam cloud save together in a nutshell turned on or off by the publisher) just noticing supermarket simulator and fast food simulator can benefit from this feature when your friends cant join or you wanna quickly change the host.

Edit:
More feedback: Maybe remind publishers about listing the co-op and pvp player amounts in the description when getting them to write them or add it to publisher steam tags I seen a game earlier where I couldn't find that anywhere on the page. Still seems like steam cares lately about QOL feedback. be neat if it had a like co-op tag with 2-4 etc. Leaving more space for a short description.

Maybe I just overlooked this somewhere and its just ranty but meh. Cheers.