That right click will be the question. It would certainly have to go through Bluetooth.
Now the thing is that most styluses that do have additional buttons, most of the time are pressure sensitive. The PinePhone doesn't have that pressure sensitive digitizer in the display making it incompatible with any of them.
This essentially eliminates the type of styluses you would find for example with the Surface Pro 3. The stylus with the SP3 can be connected via Bluetooth to utilize those additional buttons but it can operate without being synced. While it is an active stylus, it operates completely differently than the Bamboo Tip - the stylus with the SP3 is an alternative to the passive pressure sensitive styluses (both require additional layer/s in the display itself). Those can have some issues with screen protectors but the usual complaint is that they increase any paralax effect making precise drawing harder.
The active capacitive ones like the Bamboo Tip, end up working like your finger (except they need power to generate the current which would be picked up by the run of the mill display in phones within the small surface area of the tip). They aren't pressure sensitive and there are options that go for cheaper like this one:
https://www.amazon.co.uk/AICase-Precisio...147&sr=8-5
Those active capacitive styluses are like the rubber ones you can grab for a few bucks except with a smaller surface area for the tip. Neither of those should have problems with screen protectors. However I don't know if someone is making a version of those "dumber" with a button (maybe in the same style as those Bluetooth selfie stick remotes).
PS: The only usage for a button on those non-pressure sensitive styluses I can think of, would be take a photo or act as "Play" button? iOS and Android are wholly unfit for such additional input :|