Short answer is yes, but......, the arp in the montage need to be examined b4 they are dismissed, especially if you want to roll your own. Many of the user arps are multiple tracks, and have chord recognition voicing logic that are unique. They have to be played with and some are amazingly dynamic with suprises that have to experienced and then you could try to recreate them. With all of the stuff you can program on the Montage, the arps are probably one of the areas that the factory dudes are way ahead of anything that we could reasonably do. With that said, you can program your arps and there a 3 basic chord voicing alternatives that are all totally different approaches. The mega acoustic arps are really worth playing with, and would be pretty tough to duplicate without a bunch of work.

https://www.yamahasynth.com/blog/arpeggio-making-101-montage
https://www.yamahasynth.com/resources/arpeggio-making-101-montage-ii

https://www.youtube.com/watch?v=MqYI32Lp55k
https://www.youtube.com/watch?v=NJhpLjpZFq8

"Like a step sequencer" would use a program on the PC/Mac first. Links provided for on-board tuning of the ARP to set the correct parameters. Also showing different techniques for how to construct ARPs such as the Mega type mentioned.