This account and accounts that I own ( @phanpy , @checkweathersg ) now have #AltText for both profile picture and header.

Available on Mastodon 4.6 https://blog.joinmastodon.org/2026/06/mastodon-4.6/#:~:text=possible%20to%20add-,alt%20text,-for%20profile%20pictures
Editable and viewable on #PhanpySocial too.