Hi I would like to ask you whether you have any workaround?
When I want to create a personal hotspot with my iphone (which does not have a sim card inserted) it does not work, because to create a personal hotspot the iPhone needs mobile data.
Another option would be to create an ad-hoc-network from the mac itself: But this feature is very risky and unsecure as it has no password protection anymore: http://www.delora.com/advice/networking_guide/adhoc_wifi2/
Also it is possible to integrate an airdop-like function (no internet connection needed) to BTT. Look here: https://developer.apple.com/documentation/multipeerconnectivity
Is there any progress Andreas? Thank you!