Nah, multipliers are locked on mobiles, but its not really an issue. It's much better to simply lower the multiplier and just boast up the HTT speed for the best results.
Venice cores will probably overclock just as well if not better than mobiles, and they many more vast improvements so I think that's the better choice.
AMD seems to have a very good variety of overclockable cores, the mobiles aren't just in a class on their own anymore.