What exactly happens when you hit 'restore'?

What does the "Restore wallet" option do in the GUI? Does it just make a new wallet folder in /.bitcoin/wallets/[nameofwalletfolder]/ and copy wallet.dat there, or is there more to it? Also, how is the name for [nameofwalletfolder] decided? I’m guessing it won’t overwrite an existing wallet.dat if you pick the same name for the folder, right? Honestly, I probably won’t bother with this feature. Seems easier to just create a folder with the name I want and drop the wallet.dat file in there.

That's pretty much what it does. The user types it in a dialog. It cannot be the name of a wallet that already exists. Because not all users can figure that out.

Well, if you're going to run Bitcoin Core, especially nowadays when you need so much storage space, I think you're not going to be the kind that doesn't know how to copy the wallet.dat to a folder manually

I used Restore Wallet and chose the wallet.dat file that was originally created in 2017 but copied from an old computer three years later. The name I chose was 'w1'. The Bitcoin Core software (v. 28.1.0) took 9+ hours to complete the 'Restore' procedure. When it completed, the wallet is showing 0.0000 mbtc, and no recent transactions. This is the wallet I encrypted and lost/forgot password to back in 2017. It has *some* bitcoin and I planned to try a few password combinations, once more. Two questions: 1) could 'w1' name be a problem? Is it possible old wallet.dat needs an 'old school' name to be recognized by the current bitcoin core software? 2) I never saved the full FOLDER when the old computer was still operational - only the wallet.dat. And I read on the forums here the wallet.dat file could be corrupted, and I SHOULD HAVE saved the full folder containing wallet.dat What is my next step to see if I can even 'revive' this wallet - in the new software - so I can try to remember my password? I tried Open wallet and Migrate wallet - but it's likely I made a newbie mistake that prevented me from properly 'loading' the wallet and seeing my btc balance in GUI

That means it was rescanning the wallet. No, the name doesn't matter. That is possible, and any data that was not compacted into the wallet.dat at the time that you made the backup would be lost. It is restored so you can try to guess your password. That is independent of whether any transactions are found. You can try to rescan it again with the rescanblockchain RPC to see if it finds your transactions.