Great topic. I think the answer will depend on the details of what you would like Metoidioplasty to do for you. You mentioned it as something in addition to pumping to increase size. There's some debate about this: Dr. Miro used to say that Metoidioplasty increases size by 50%, and I haven't heard him walk that back, but the general consensus is that surgery doesn't increase size, just better exposes what is there (and maybe that's what Dr. Miro means.) It may depend on whether or not the suspensory ligament is cut--not all surgeons do this.
Also, testosterone does not necessarily cause permanent growth, so if someone goes on T to get growth and Meta with the plan of going off T in the future, they should be prepared to lose length, even after surgery. Almost every bit of documentation out there says the growth is permanent but this isn't always true. (I know from experience and I was surprised because it was the opposite of everything I'd ever read about the effects of T.)
There are certainly lots of non-binary people who opt for Simple Metoidioplasty and I'm sure many of them are quite satisfied. But if your goal is increased size without Testosterone, you may be disappointed with results, unless you're already generously sized.
Ultimately, a consultation with a surgeon who is experienced at working with non-binary individuals would be a good idea so that you can get a more accurate assessment of whether or not surgery would satisfy your goals.
Wish I had a more specific answer for you but I hope this helps!