I just had a look at Adobe's Spark app.
The web interface allows one to upload fonts to their interface to use when creating social media posts with the app.
They do enjoin the user to make sure the EULA allows this use, but I'm not sure how to proceed. The fonts are restricted to the user's account, and projects exported as jpgs or pdfs, so the fonts don't go out in "wild".
In all fairness, it doesn't seem too far off desktop use, but what do people thing?