I can't say its "easy" to make your own?
I'm not sure the "sequence" of commands here is the same as a sequencer; I think that the "sequence" here is more about controlling MIDI devices parameters, perhaps in order, rather than triggering notes.
As mentioned, I could see myself using one of these to control settings/select patches on a number of devices; heck, if I changed my switcher from the Quartermaster to a MIDI-capable one, this could be the only unit required on the floor and the pedals themselves could be on a shelf in a rack.