I'm not sure if this would be a solution for you, and I've never used it myself, but I found this interesting secrets management project a few years ago that I always find myself thinking "is that what I want?":
Like I said, I haven't used it, I can't vouch for it, but it looked interesting for my own use, which is personal/small team, with an emphasis on simplicity.
https://git.sr.ht/~egtann/shh
It looks unmaintained, unfortunately, and a link in the README to an article that gives some background is broken (but archived: https://web.archive.org/web/20201128160302/https://www.egt.r...)
Like I said, I haven't used it, I can't vouch for it, but it looked interesting for my own use, which is personal/small team, with an emphasis on simplicity.
Take that for what it's worth! :)