I’ve decided to use the Sonoff SNZB-01 button purely on price. In the UK the IKEA buttons are £6 each in store, and I can get the Sonoffs delivered in a day or two for less than £7 from an official UK distributor (or so they claim).
Apart from one Shortcut button, which has always been a bit crap to be honest, I only have the On/Off buttons. I have mostly used them to provide four toggle actions (they replaced four action Aqara buttons) but I actually found three was enough. So the press, double press, and really-very-long-indeed press of the Sonoff is right for my needs and I do prefer the single button. The Sonoff buttons don’t have anything approaching the build quality (and don’t like having the Zigbee channel changed on them, but that isn’t something you do too often) and can be a little clunky, but on the other hand the IKEA buttons have far too soft an action and the magnetic mount is a nice idea that is far too weak in practice (I’ve actually long since limited them to controlling things that I don’t mind accidentally turning on or off and in places where I can see where the button goes as it flies off the mount).
Driver wise, I am sure something local will come along soon, if it hasn’t already. I can wait or I can probably do it myself if I can be bothered (I just can’t get interested in the Edge drivers for some reason).