[raybb]

Have you tried Bitwarden (vaultwarden for selfhosted)?

I'm pretty sure, you're able to share access to a login with just one person. Or make a "collection" of accounts and give that access to individuals as you wish.

https://bitwarden.com/help/about-collections/

[zeeZ]

Bitwarden sharing requires the use of collections always. It's either in your personal vault or your organization's vault, at which point an admin can see all the entries and assign them to 0 or more collections. If you have strict rules on who can create, access and edit entries, it's a bit painful to set up.