I don’t play… any of those. But I would recommend doing a bit of googling to confirm that ApeLegs and The Finals have an anti-cheat that supports linux (I think ApeLegs is EAC?). And I would very much check that World of Warships won’t ban users for not running windows. Competitive multiplayer and live service games are still somewhat hit or miss on linux/steam deck.

Aside from that: Games bought directly on Steam have ridiculously nice refund policies. But you can often get them for cheaper (even during sales) from legitimate resellers so it is good to get into the habit of checking https://isthereanydeal.com/. https://www.fanatical.com and, to a lesser extent these days, https://www.humblebundle.com/ are great sites to get a good number of good games for a great price.

And there are key resellers/grey market sites like Green Man Gaming* and CDKeys but, if you are going that route, just pirate it since it is less of a burden on the developers that way.

Other stores work, to varying levels of hassle, so it is worth keeping an eye out for https://www.gog.com/ deals and https://store.epicgames.com/ freebies.

*: Just to speed through this. Yes, GMG is still a grey market site. They got caught the better part of a decade back when CD Projekt Red and Rebellion called them out and even revoked a lot of keys. And they had been known to source keys from strange locations which is why so many Call of Duty keys were ROW and games had no pre-order bonuses. For a year or two they acknowledged this and marked what games they were official resellers for and what they weren’t but… they stopped doing that. Speculation is they buy in bulk from lower purchasing power regions, like Brazil, and then sell the keys at crazy mark-up. So, at best, you are letting them screw you over while also encouraging more developers to stop doing regional pricing.