It depends on what style you go for, there are several types which have different solutioins. Mine is a 46mm ID x 73mm width. I use a Praxis converter which, when installed looks just like a normal external BB. There are other options for this type which require Delrin spacers which I’ve not tried.
You can also get a Sram PF to BSA adaptor, you screw a normal BB in to it and press it in the frame. For me, the trouble is it’s made of Nylon which I don’t hold much hope for in the long term. An Alu one would be great as long as it hade a decent interface in the ctr of the BB shell.
The other type can have have up to a 92mm shell width, there are others but can’t remember the exact sizes. Hope make servicable BB’s for this type, I understand they’re making one for the other style BB shells too. King are releasing something this Spring too.
Other, more durable solutions will come soon. It;s just a matter of time. I hope.