There’s a ton of game launchers, for instance this one just came out the other day and allegedly launches your games from Steam/Heroic/Bottles/etc. Not sure if it’s what you need but it seems weird there wouldn’t be an alternative to Playnite: https://flathub.org/apps/details/hu.kramo.Cartridges

Screensharing looks like something to wait on though. I’ve heard of people getting it to work but seems finicky

Edit: Looks like Playnite has distant goals of supporting Linux. Could be a race between these two apps for you to see which one gets working first