Dependencies need review?

I found that PyWavelet is used by wip.signal module, but is absent from lazylinop project dependencies. There may be others package like this?

On the other side, I am wondering if it is desirable to make lazylinop package depends on external software that may be rarely used by most users?

For instance, I am thinking about mpi4py (and maybe pyfaust) which are currently required by lazylinop. It could be possible to ask users to install these packages themselves if they use the functions which depend on them (and to fail "cleanly" with an error message inviting to install them). I think it's quite common to do like this in other similar projects.