After a year-plus of curiosity about it, we finally gave homemade vegan "cheese" a try. The recipe we tried claimed to be Pepper Jack.
Did it taste like Pepper Jack?
Not really, but it was analogous.
Did it look like Pepper Jack?
Not really. Too yellow, slightly grainy. Graininess might have been because I cut short the final step of stirring by a minute because my arm was tired.
Did it shred like Pepper Jack?
Claims were made that it did, but we belatedly realized that we don't own a grater.
It was too soft to shove through the food processor, but I feel like you might have been able to do it by hand.
We had to tear off chunks to make pizza.
Did it melt like Pepper Jack?
This is a weird one. I could totally see using this in a crock pot for nachos. Or mac & cheese. It was that sort of melty, but it didn't quite ooze right for pizza. Our chunks were pretty large and didn't manage to achieve total surface coverage. They spread out in the same way cookie balls do.
Did it taste good?
Yes. We'll probably go this route again.
I have a hunch that the texture problem might boil down to the pH. Lemon juice and onions do make it slightly acidic. Optimal pH for the yeast to do their work is around 4.8 - 5.0 Note that yeast fermentation stops at pH 4.2, so you don't want to overshoot this. Agar and starches can gel at almost any pH between, but agar should not be exposed to pH more acidic than 6.0 for too long. The cheesemaking you do is likely too short of a time period to affect it, but I felt like adding it for completeness's sake.
I would try and experiment with the proportions. I know that universal indicators are not in most (normal) kitchens, but this honestly sounds like a cool experiment! :D