Seems very good, especially since it mirrors apps like instagram in a way. Not sure about the watermark though, it's not a huge deal breaker but could be annoying. I wanted to buy the witcher books after completing the 3rd game, but, they have a big Netflix print on the box and each cover. I like the show, but that annoyed me so I haven't bought them yet.
Also the subscription tier to me didn't sit well, as what if the quality of peoples free posts went down. Until you mentioned the idea of utilising that to do things like lessons, that's a great idea. Giving the odd starter freedy would be good to get people involved in the more intermidiate lessons, some financial appreciation for the teacher who is working on their classes as well as encouraging people to pay attention, whenever money is put on the line by someone they're more inclined to take it seriously and stick with it.
Everything needs time to work out kinks and react to users, but overall that's a nice step into new territory. Great run down, I'll have to check it out myself. Sometimes it's nice being able to add in a picture with a quick description like on instagram. I saw someone talk about why Tiktok and instagram are so addictive and it comes down to quick jolts of dopemine rather than the slow release from engaging with larger longform content.