Hello @apuntigam, can you run steam from a terminal and share the terminal spew? Also, just to check, what does apt policy libc6:i386 give you?

It may also be interesting to check if any 32 bit OpenGL application works. I used to recommend a 32 bit build of glxinfo from mesa-utils:i386, however, Ubuntu no longer provides a 32 bit build of this since 20.04, which Linux Mint 20.x is based on.

Thanks, I've got a couple disjointed ideas to ponder.

First, you've mentioned that you've installed and tried the Valve-provided Steam package, which puts the Steam client in ~/.local/share/Steam, but your terminal output has ~/.steam/debian-installation which is what the distro-modified Steam package uses. Historically, there's been trouble when switching between the two package variants due to folder layout differences. If that's the case, moving ~/.steam and ~/.local/share/Steam somewhere out of the way should let the Steam client do a fresh bootstrap. Afterwards, if it's working, then you can close Steam, then copy/move the steamapps folder from your previous Steam install, which you set aside, into the newly bootstrapped Steam install to get the downloaded games back into Steam.

Second, I suspect that something went wrong with unpacking and/or updating the Steam client. If that's the case, you should be able to run steam --reset to tell Steam to re-bootstrap the Steam client. Alternatively, you could try manually opting into Steam's beta client to trigger an update with something like echo "publicbeta" > steam_install_folder/package/beta

Between those two ideas, I'd check if ~/.local/share/Steam exists and has a semi-recent timestamp on some files. Maybe check if it has games in ~/.local/share/Steam/steamapps/common. If it does exist and is the older Steam install, then that hints to us that apt decided to swap Steam package variants under your feet and proceed with the first idea mentioned above, otherwise, a less aggressive approach can be tried with the second idea.