I think you would be fine using a common BB mid-drive on this setup. The BB shell does appear to extend beyond the bearings. If it did not then It would possibly bind with any external bearing bottom bracket which is most of them these days.
As for other bikes using this concentric pivot design:
- DMR Bolt Long
Has bolt on vertical drop outs but you could make your own so they are horizontal for easy tension
https://www.vitalmtb.com/product/guide/Frames,7/DMR/Bolt-Long,25641
- NS Soda Slope
Has horizontal drop outs for chain tension
https://nsbikes.com/soda-slope,125,pl.html
- F.U.T.R. Beta ebike frame
Has integrated battery box that may get in the way of the mid-Drive unit
http://www.futrelectricbike.com/product/beta-snow-white/
Both the Soda Slope and the DMR Bolt are going to be more dirt jump/slope style bikes. Smaller frames with less emphasis on handling and braking. I think that means super fun but someone looking for a high speed Long travel machine similar to a Down Hill bike might not want to use one of these.
In my mind the sacrifice of a Dirt Jump style bike is pedaling efficiency. Once you have the motor that goes out the window so I think it would be great. Slam the seat all the way down since you aren't pedaling and use the motor to get from one riding zone to the next. But I understand not everyone has the same goals in mind. My ebike goals are almost exclusively late night Urban Hooligan stuff.