Turned based on pausable stuff can reduce stress by allowing for thoughtfulness, and even single player games can be done together through strategizing, while also not requiring the 2nd person if they aren't available. To that end, I'm going to recommend Slay the Spire, Dicey Dungeons or Broken Age. Then probably some kind of tactical game, Darkest Dungeon, Loop Hero or Shadowrun. After that, maybe some kind of management game, Cities: Skylines, SimCity, Stardew Valley, Humankind or Against the Storm. If you want to go deeper, Crusader Kings, Dyson Sphere Program or Wartales.
Real-time games that require using multiple sticks/buttons/aiming+moving at once are inherently more difficult to start without the muscle memory, so I'd look to build that up with games that have simpler controls starting with Vampire Survivors or Brotato. Then I'd probably do some kind of non-shooter first or third person game, thinking of Escape Academy, Firewatch or Superliminal, Amnesia (maybe). Then a combat first/third person game Assassin's Creed, Battlefield (Campaign), Mass Effect. Then maybe something that's got combat plus extra stuff, Atomic Heart, Deep Rock Galactic, Dead Space (maybe), Doom, Prey, Wo Long, Remnant. After that is really PvP stuff.
If you just want more readably accessible stuff, A Short Hike, Disneyland Adventures, Peggle, Plants vs Zombies, Bejeweled, The Walking Dead from Telltale (maybe).
I also pulled every game on this list off of Xbox Game Pass, so that might be a good way to try a bunch of different games for cheaper.