Polenta instead of breadcrumbs?
You can use definitely use polenta/cornmeal for breading, but it'll tend to be noticeably more crunchy than breadcrumbs are.

An obvious comparison is cornmeal fried fish. People make it multiple ways: some just dredge in cornmeal so it'll add a definite crunch, while others use a batter which will soften it up. The moisture from whatever you've coated matters too. I'm guessing pork loin isn't going to release a whole lot of water, but if you're marinating it perhaps you'd get some from there.

Since polenta is coarser, I'm guessing you might want to err on the side of caution, to avoid crunchy turning into gritty.