I collect a lot of certs for fun, but most have not been helpful. I still like to collect them anyway. I think OSCP was the most legitimately useful in tech https://www.offensive-security.com/pwk-oscp/ PMP has been useful to take on Project Manager roles, but really PrM roles aren't all that exciting to begin with. Still helps when you want to run your own projects. I'm currently studying to be a certified parliament…
just out of interest, what do you do with the offensive security knowledge?
Pentesting really requires "full stack" systems knowledge, from networking, to OS, to API analysis, malware analysis, binary reverse engineering. OSCP is an applied cert, so it really forces you to be able to leverage knowledge in a practical way.
However my favorite benefit of offsec is really being able to see things from an attacker's perspective. This has been super valuable in many situations and I've found I'm many times the only person in the room with an awareness of an adversarial mindset.