MTH has a European line. This link will take you to the current online catalogue: https://mthtrains.com/sites/default/files/catalog_files/2017_v_2/index.html#
Lenz makes O scale: https://www.eurorailhobbies.com/lenz.asp There may be others as well but this is all I could find.
At one time, Pola, Lima and Rivarossi made 2 rail O; I actually have some and they are not bad. When I got this, it was missing its buffers, so I made some out of roofing nails... Edit: It has the same motor/drive as their Fairbanks Morse model. Mark in Oregon