Information regarding UN300 and UN100 (new Shimano Bottom Brackets)
On the german Shimano site the UN300 is a bottom bracket designed for (e-)MTB. It is advertised as available in 3 versions: standard, E-type and closed gearbox (I think it is the spindle&amp;co. without the housing). Different lenghts are offered.
It is advertised as part of the "Shimano Acera" family of products.

The UN100 is advertised as part of the "Shimano Altus" and "Shimano Tourney" family of products. It explicitly mentions being compliant with two specifications only (D-NL and LL123)