Many such cases
Many such cases
I actually do use acrobat for legal document work
It good for adding signatures and making changes to pdf format schtuff
If that’s your only use case you can also use Xournal++ on Linux which does the job.
Of course your choice of OS is totally up to you and you don’t have to justify it to anyone, just letting you know the tool exists.
Well, it uses existing PKI/CAs (ie, same as your browser), which I’m not sure GPG supports? I might be wrong.
You could certainly use GPG, but it’s not what others will be looking for. Depends on your use case, I guess.