You may want to check out isthereanydeal.com to build your wishlist. It allows you to set the price thresholds at which you want to be notified and also supports other fully-legitimate (as in devs actively collaborate with them and get paid) stores than just Steam. Many of which sell Steam keys which are codes you can redeem in Steam to activate the game there.
You have all the benefits of Steam games such as no to little extra fiddling to play games on Linux, library and cloud save sync, Steam community and workshop content, playtime tracking etc.
The only real downside is that you’re not covered by Steam’s super lenient refund policy, which is actually quite good to have, since not all games run perfectly on Deck yet. If you buy from other stores, it’s usually hard to refund games that you’ve already redeemed. But if you’re fairly confident that it will run and you won’t refund it, you can sometimes find really good sales “off-season” this way.
Hope that helps :)