What is the difference with Friend?
buddy-auth authorization/authentication facilities are more low level and less opinionated than friend, and allow you to easily build other high level abstractions over them. Technically, friend abstraction can be built on top of buddy-auth.
By design, buddy has authorization and authentication well separated. This helps a lot if you want use only one part of it (ex: authentication only) without including the other.
In summary: yes, you can use buddy-auth with liberator.
Can I use buddy-auth with pedestal?
Although is not mentioned in this documentation, you can use buddy-auth with pedestal without any problems.
Can I use buddy-auth with catacumba?
The design of buddy-auth api is intrinsically blocking just because ring and ring based abstractions are also blocking. However catacumba is asyncronous toolkit and it comes with its own, builtint variant of buddy-auth designed for asynchronous workflow (reusing the underlying buddy-sign, buddy-core and buddy-hashers modules).