Lego games like Lego Starwars has already been mentioned and I will second those (especially the newer ones that have split screen).

Divinity Original Sin is also great.

 

Honestly most games I can think of have already been mentioned or don’t seem like that great of an option since it seems your partner isn’t normally into gaming.

But I will suggest some anyway just in case

 

Starcraft 2 has free online multiplayer which includes a COOP vs AI mode.

There’s also a 2 player campaign adaption of Warcraft 3’s normally single player campaign. Although it might only be available for pre-Reforged.

Also I didn’t know about it before now when I googled it just in case but apparently SC2 also has COOP mods for its campaigns.

 

You mentioned having a Switch so I will recommend Advance Wars Reboot and Wargroove 1 & 2, although there are no COOP campaigns but you can play multiplayer maps.

Besides Advance Wars Reboot Camp on Switch (or the originals for Gameboy, which you could play with emulator), there’s also an online fan site called Advance Wars By Web where you can play advance wars in the web browser, although there’s no single player.

Wargroove is also on Steam and besides the campaign and regular game itself there are puzzles.

And speaking of Puzzles, card games tend to have Puzzles. I haven’t actually played Magic, Yu Gi Oh, etc. so I can’t say for sure whether they have any, but there’s puzzles in Faeria. (I would’ve recommended Might and Magic Duel of Champions, it had some great puzzles, but Ubisoft shut that game down many years ago)