VS Code (i know it's still MS but I do C# .NET work and rider is too expensive, I don't want a subscription for an IDE)
VSCodium is a thing too if you want to un-Microsoft even further.
I use it for C# development on Linux and it works well.
getting a password manager
Bitwarden and Keepass are usually the go tos, depending on your use case.
then a new browser
Firefox or if you want to decouple from Mozilla as well, Librewolf works pretty well.
potentially a Google pay replacement
I'm not aware of any open Google Pay replacements other than taking a card with you.
As soon as you get rid of Google on your phone, you get rid of Google Pay.