Short answer: Yes and WebDAV is the best method (see update below). There are apparently some issues related to pClouds integration with iOS Files.
Via Files Method
pCloud has been requested a few times and you can do this via the Files app:
In Strongbox > Add Existing Database > Files > pCloud > Browse
However there have been complaints about the integration by pCloud with people saying that their integration doesn't sync properly so you would need to be careful here.
Unfortunately pCloud do not provide an SDK for apps like Strongbox to directly integrate (like e.g. Google Drive, OneDrive, Dropbox) nor do they support open protocols like WebDAV or SFTP.
UPDATE: 29 March 2021
It has been brought to our attention that pCloud now supports WebDAV so you should be able to use the following URLs to access/update your pCloud databases via Strongbox: