Hmm... Unity WebGL has worked correctly on Mobile Safari since 2013. Support has probably been flawless since around 2019. It has been supported in all the ways that matter for a long time.
I wasn't aware of that. The Unity 6 Preview announcement from just this year had a lot of stuff around iOS and Android browser support:
From the article:
Android and iOS browser support has arrived With Unity 6 Preview. Now, you can run your Unity games anywhere on the web, without limiting your browser games to desktop platforms.
I should have said that it's not officially supported. For client work, we prefer not to choose an engine that may not work on a few devices and which we have no ability to fix.
However, mobile browsers will be supported with Unity 6 web exports, still experimental currently AFAIK, but that should become a viable option soon.