Recover whatsapp chat backups after reset without access to old number

I made a factory reset of my phone, which had Whatsapp linked to a deprecated phone number.
Before the reset, I backed up the chats both on Google drive(*) and on the simcard (a crypt12 file).

I hoped I'd be able to recover the chats after signing in with my new phone number, but this isn't happening on its own.

Furthermore, I can no longer log in with the old phone number (as it is deprecated), and cannot do the number transfer.

1. Is there any way to force a recovery of previous whatsapp chats on a
   phone with a new number?




2. If not, is there at least a way to access the text content of the
   backup files (either on Gdrive, or on the sd card) from e.g. a
   computer, or are all the chats definitely gone?

(*)a similar question was posted here, but is unanswered and only refers to restoring from gdrive, whereas my question also mentions a local backup, and the ability to access the chats even from a different platform as whatsapp.