starbright
The differences between work profile and private space are minor. Under the hood they use the same implementation, but they may be treated differently by profile-aware apps like launchers. Unlocking Private Space requires a biometric unlock, while unlocking Work Profile doesn't, but those might just be the defaults. You can have both at the same time in any case.
Work profile and private space are both always-on (you have a quick button to turn them on/off), alongside your main profile. You're probably thinking of separate User Profiles, which are the ones you need to manually switch to and from. I don't use those.
The sharing interface allows you to choose to share across profile boundaries (with some exceptions). My usual "flow" is taking a photo with main-profile GCam (no network access, no Google Play Services available), which gets saved locally and synchronized to my Immich photo album. Then I can hit 'share' -> 'work profile' -> 'Whatsapp' and send it to a friend, while Whatsapp stays installed on the work profile side.