I do something very similar, but I don't have an oven so I make
pancakes. I've talked about this a number of times on here.
I usually use two different ingredients, rather than one. For pancakes, I need something that holds together well
enough to flip, so I often add flaxseed if the other ingredients need it. Oats and chickpea flour are good binders.
I've used green buckwheat, oats, quinoa, teff, kaniwa, millet, lentils, rice, urad dal (which is translated as lentil,, but I think it's a kind of mung bean maybe. Same size and shape, anyway), along with rye and barley, but those last two contain gluten.
I haven't tried peas. That sounds like a good one to incorporate!
I rarely remember, but sometimes I mix in poppy or mustard seeds, both of which I grow.
One thing I keep meaning to try is adding fermented nut or seed
milk. I have cultured sunflower milk almost every morning in my porridge, and it would probably be a nice addition to a pancake, too. The fat in the seeds might make it more moist.