*Let's assume I created a native wallet in Core. I'll encrypt it with my password/passphrase before transferring funds, obviously. For me, just backing up the wallet.dat file is enough, but to prevent snoopers from accessing my wallet.dat and seeing the balance and transactions but not being able to spend, I'll add additional encryption, perhaps using gpg or aes, or perhaps something simpler like moving the file to a Veracrypt container or (even easier) to a KeePass database file.
So what I am trying to achieve is to have a physican backup of a core wallet, but being encrypted

I am putting this emoji because it looks like nobody has done it, or hasn't seen this thread yet.
Your approach looks like what I currently do, more or less and it's a common method. To be honest, encrypting the wallet.dat and the disc where it lies with another password is more than enough. It doesn't need extra gpg encryption on the file itself.