Agree with a lot of your arguments, but you won’t need to leave the Apple ecosystem because of the secrets management. I find the Passwords app works well, and so I use it most of the time - except when I am creating a new secret or changing one. In these cases I use my off the shelf secure password manager, the primary (backed up) password store, which is good enough for these isolated cases. Moving on from the change events, the new/changed secret makes its way into Apple Passwords usually without much prompting - the app almost always immediately asks if I want to save that changed credential in Passwords, which is exactly what I want.

This trades off security, and for that reason I don’t follow this practice for all secrets; it’s mostly a convenience.