If the content is not stored locally and DRM free, then you don’t own it.
Have fun managing tens of TB of backups. I have given up on that quite a while ago, DRM-free is just not a practical for the amount of digital content you collect over the years. It’s a nice to have thing that comes in really handy sometimes (e.g. watching movies on unsupported device like VR headsets), but it’s not a solution for digital ownership. In some ways it’s actually worse, as you can’t practically resell DRM-free copies, as you don’t have a proof of ownership. You’ll also miss out on updates for new technologies (codecs, OS versions, etc.).
This needs a legislative solution or some NFT-like thing that gives you a certificate like “You own this, feel free to pirate if we go out of business”(digital signed by company).
Steam, but you’ll have to manually search around the forums to see which games does it and which doesn’t. It’s not exactly a well advertised feature, but integration of Steamworks copy protection is optional. Most of the games that are DRM-free on GOG are DRM-free on Steam too.