If I wasn't virulently anti-helm I'd probably help maintain it, as it is I treat Helm as necessary evil but never write any charts ^^;
Another idea I just had yesterday, and which I've seen partially executed by others, was serverless Vault/OpenBao - the tricks I've seen used various FUSE filesystems, but I wonder if an S3-compatible backend couldn't be added one day :)
You should read this RFC: https://github.com/openbao/openbao/issues/1340
If you use that with a PostgreSQL backend (which doesn't require raft and has faster leader changes), it might be possible.
Feel free to drop me a mail as well, email is in my profile.