Yes and no. I can see the folders but a cannot get a path with RMB or [shift]+RMB.
And also copying the pseudo path from the explorer adress bar “This PC\Fairphone 4 5G\Internal shared memory\DCIM\” results in an warning message from Duplicati that this path doesn’t exist.
Your link to the MTP entry of wiki gives the answer, why:
Windows does not assign drive letters or UNC pathnames to devices connected via MTP; instead, they only appear as named devices in MTP-aware applications such as Windows Explorer. Compared to devices that implement USB mass storage, such devices cannot be accessed programmatically by scripts or normal Windows programs that depend on drive letters or UNC paths. Instead, files must be manipulated using Windows Explorer or applications with specially written MTP support.
And after reading your post and some facts about MTP, I think, that there’s no hope doing my android backups with Duplicati. Too bad, I would have liked to do that. I’ll have to look for a similar android app.