AFAIK many people use a bouncer (e.g. ZNC) for connecting to IRC. ZNC at least supports individual backlog for multiple devices. So I think that is a fairly standard solution.
As someone who was essentially constantly on IRC back in the 90s to early 2000s, IRC is just significantly less usable "out of the box" than Discord or Matrix; either is significantly easier to teach someone to use, especially multiple-device.
The ship has sailed and I don't think IRC3 will ever get traction even if it ends up actually being good.