Wouldn't decreasing the buffer pressure to zero make it into a kind of Cooper-Hewitt lamp? Just with oxide instead of liquid mercury cathode, but the discharge environment otherwise the same.
Yes, these tend to operate at 10x higher currents than fluorescents used to do, leading to a completely different loading, working temperature and mercury pressure.
But CH's were also started by a HV pulse via a (capacitively coupled) external electrode, which should work with the small solid cathode even better than above the flat, smooth mercury pool surface.

Any hard facts to confirm this? Anyone opened the lamps and did electrode analysis? Also small MH lamps you are usually playing with have tiny electrodes, they need to be heated really hard to sustain circa 1A emission current, if you compare them to HPM electrodes of say 80-125W wattage.

Cool. Thank you!

Looks like for US market, it's 120, 208, 240 and 277.  For Canadian market it's 120, 208, 240 and 347.

So does it go higher than 277? Or only for Canada? Sorry.

7 Optional multi-tap ballast (120, 208, 240, 277V). In Canada 120, 277, 347V;
ships as 120/347.

The recent Osram/Ledvance MV lamps and most Chinese MV lamps, uses thorium emitter, and their electrodes don't glowing brightly during starting.

Do you have any of such lamp in person? It seems to be a very old tech, hard to get any surviving lamps. And, cold MH lamp absolutely equals cold mercury lamp, just a discharge in pure Ar al low pressure.

I am going to buy a TFM Lithona Floodlight. The problem is on the voltage sheet, it says TB. It doesn’t describe what that means, and it has a number 7 next to it. Does that allow for 120 volts? I was kinda stumped with it.

So why mercury lamps with thorium emitter, don't have brightly lit electrodes as well?