I'm not really well versed with codecs, but is it up to the devices or the providers (where you're uploading them) to handle playback or both? A couple of days ago, I tried to upload an Instagram Reel in AV1 codec, and I was struggling to preview it on my Samsung S20 FE Snapdragon version (before uploading and during preview as well). I then resorted to H.264 and it worked w/o any issues.