I haven't used this Pep device but have eyed it. More common in Europe than US.
https://www.saveritemedical.com/products/pari-o-pep-oscillating-therapy
Not sure about how you clean or sterilize it. Since I breathe out only through these devices (rather than in and out) I don't worry too much about sterilizing it.

I have used the green acapella choice (it used to be called) and I think I prefer Aerobika marginally, likely because it seems quieter.