Is there anything wrong with simply maintaining a pgp encrypted text file that is routinely edited and backed up and never stored on the same device as the keys?
Your password manager is not just a vault. It’s a forensic record of every version of you that ever touched the internet.
https://untraceabledigitaldissident.com/hidden-accounts-using-password-manager/
Discussion
For what purpose? A roll your own password manager?
Yes
No. It’s more maintenance but if it works for you then go for it. My only concern would be password length and quality since even offline mangers like keepass have generators. You could use a standalone generator or dice and a word list. If your threat model is purely digital and not evil maid you could old school air gap with a notebook and pencil. Can’t hack paper