- I have to add my personal sonatype credentials to bamboo
As I mentioned, instead of your personal credentials these can be a specifically created account. We use such an account for Jitsi.
- snapshots have a limited retention policy. Whereas artifacts are never deleted from our archiva instance
AFAIK this is still true. However, I don’t think it matters for snapshots. If you do want to keep a history, you could deploy to both repositories.
The problem with multiple repositories as a consumer is that you’ll never really know which one you’re ending up with.