You want a specific tool for each of these use-cases. Choose one from the list for each use case.
1. Private messaging: Signal, WhatsApp, Cwtch
2. File encryption: age
3. Encrypted backups: age + a Reed-Solomon encoder for catching flipped bits
4. Digital signatures: minisign, signify, OpenSSH signatures
The problem with GPG (and with PGP in general) is it tried to do too many things. Complexity is the enemy of security.