What's the current guidance for Onedrive, FSLogix and redirections.xml - in or out of the profile?

You referring to roaming OneDrive?

Yes on non-persistent workloads.

On-prem, I would typically put OneDrive in the Office Container. On cloud, put everything in the Profile Container. No redirections needed.

MS if looking to change recommendations for only using Office container with a separate profile solution, not on top of fslogix profile container. So I have switched everyone to profile only and many of the headaches I had in the past are gone. Just make sure to setup storage sense and dehydration on the profile to roam data that isn't used frequently to cloud only.