IMO, your suggestion assumes that today's government and tomorrow's government will have the same ideals and viewpoints on pornography, and not for 1-2 administrations, but indefinitely. Being able to reverse engineer someone via metadata is possible as is, and likely will become even more finetuned as we AI evolves.
As an American, there are plenty of examples under the current administration where data shared in confidence by undocumented immigrants are now being used to target them for deportation.
It's kind of like sharing data with a company indefinitely because of their current ToS, which is just a snapshot in time. Today's "helpful" approach towards data collection becomes a key part of surveillance in tomorrow's world.
Depending on your device, gadgetbridge might do the trick as an intermediary. I went from my Garmin watch -> AmazFit watch based on compatibility w/ GadgetBridge and it allows you to export the .gps files and upload to many self-hosted apps.