A few days ago he posted (then I think deleted) this, which among other things makes me extremely inclined to not believe anything he says:
In March 2019 I teased the Pixelfed mobile app. The only problem was, I didn’t know how to write one. So just like the original “federated instagram” post, I faked a commercial to build hype. It was coming along well. Then in mid 2020, I came out and put the app aside. It wasn’t until late 2022 that I found a Pixelfed react native app, and cloned it and tinkered. In 2023 I released the first Pixelfed app, but it was slow. I rewrote it from scratch in May 2024. From faking, to making!
Well, it’s kind of up to him. His NLNet grants require it to be open source and dictate what license he uses, but I don’t know the details to know if that just means it has to be open sourced in order to receive the grant (awarded upon completion not ahead of time) or right away.