Apple keeps talking about "embracing the latest web technology", and it's true that desktop Safari has been compatible for some time now, but still not iOS browsers.
And because Apple requires all iOS browsers to use WebKit under the hood, they all share the inability to run BBC BASIC.

To test it for yourself visit https://wasm.bbcbasic.co.uk/bbcsdl.html, iOS browsers will report "Exception thrown, see JavaScript console" (not that there is a Javascript console in iOS Safari, as far as I know!).