Nostur on iOS renders markdown.  And it looks great!
https://nostrcheck.me/media/008cca1f26139409b218d7991565605970376a118e0c63c5fd4bce48c57aa67b/2aa48a0942c699ecdb481f5b7d297ea2f8a03c56778dc59d7926a15e1538d47c.webp