Are there glass tubes out there that are threaded top & bottom?
As a general rule, no. Threading on atomizers is fine, and machining or molding those threads on glass would be difficult and costly... in other words, not cost effective.
Even with expensive atomizers, like the Kayfun - arguably the most popular high end RBA ever made - no one has attempted to make threaded glass.
Recently in fact, glass tanks are being made for the Kayfun by small specialty shops - they include threaded
metal fittings which screw onto the atomizer base and top, then the straight glass cylinder is sealed with o-rings - basically a carto tank type housing, that fits over the Kayfun base atomizer.
The cost of these Kayfun conversions (alone) would keep you in plastic clearos for 1-2 years. ;-)