There are 3 types of Standard MIDI Files, but only two are regularly used in my understanding. (I don’t know any application that makes, stores, reads, or uses Type 2)
Type 1 separates out different Tracks, Type 0 sticks all the data on one Track.
Pyramid has an option to use multiple Patterns in a single Track.
If you only want to use one Pattern per Track, then Type 0 is fine. One MIDI Clip in Ableton will be the data for one Track in Pyramid.
If you want to be able to Import into Pyramid a Standard MIDI File that separates out several Patterns on one Track, then you’ll need a Type 1 MIDI File.
However, there’s more in that can of worms which, if you’re unfamiliar with these concepts, will be even more confusing. Apologies. Patterns might be a bit more advanced. I know it took me awhile to wrap my head around it, but I’m an idiot. YMMV
An example of Type 0 vs Type 1 MIDI files is perhaps in Ableton when you drag a .mid file and it shows several clips spread across several Tracks in Session View. That is a Type 1 MIDI file. If it just shows up as a single clip, it’s Type 0. I think that illustrates the difference. The rest is up to you to decide if you want to take the Blue Pill or the Red Pill.
Apologies in advance for the oversimplification, but I think that explains it…? Maybe? Sorry.
For more info, MIDI.org is an excellent resource, although IMO tough to navigate to find the info I am specifically looking for. They have some excellent reference material on SMFs here: https://www.midi.org/articles-old/about-midi-part-4-midi-files