I use pass as my password manager on all my Linux boxes (with a yubikey to store GPG keys and Password Store + OpenKeychain on android).
I basically refuse to use any password manager with an implementation I can't see or audit.
I can't imagine trusting any company to handle my passwords correctly.
The only proprietary component is the yubikey which is basically incapable of misbehaving in a way which would cause me to lose control over my passwords unless I lose control over the yubikey itself.