Would that work to monitor a pedal steel. Steel, to volume pedal to that, to amp? Would I need to put an IR loader before it or could I just go straight to the amp and monitor from this pedal?
Given pedal steel -> volume pedal -> headphone amp pedal -> amp, you would hear the pedal steal and the volume pedal but nothing in the headphones from your amp or speaker.
Does your amp have an effect loop after its preamp and eq? If so, the rest of this paragraph applies: You could fx loop send from your amp to this pedal and you would hear pedal steel, volume pedal & your amp's preamp with EQ but not any color from the cabinet/speaker in the headphones. You could simply not return to the fx loop return to have just headphone monitoring for quiet practice. You could put an IR loader in front of this in the fx loop to have cabinet/speaker sounds in which case you would hear pedal steel -> volume pedal -> preamp + eq -> cabinet/speaker sounds from IR loader/pedal in your headphones.
Other alternative would be to use an amp in a box pedal with this and your volume pedal so your signal chain would be pedal steel -> volume pedal -> amp-in-a-box pedal -> headphone amp pedal. You would hear the pedal steel, volume pedal and amp/speaker/cab sounds from the amp in a box pedal. If you wanted to use this live, you would go out from the headphone amp pedal to PA for the audience to hear.
I don't know dick about pedal steel, so I don't know what types of amps are used, but am guessing clean with a lot of headroom, which sounds like a Fender blackface style amp to me. If those types of amps are acceptable for pedal steel, you could use the UAFX Dream pedal which is a Princeton Reverb. These go for around $275 used. I just bought one, but it has not arrived yet, so I can't speak to it from personal experience.