What's your boat name, model, hull # and location?
I've not seen acrylic instrument mounting panels on Amels (just acrylic switch panels), but maybe newer models have that. On my SN I had to enlarge the openings for my new B&G MFD's but that's in fiberglass and, yes, the oscillating saw is the right tool. On acrylic there's a risk of melting the material and getting a nasty ragged edge but you can do it by going slowly and rotating the blade continuously to avoid overheating it.
I see they want a 15mm / 19/32" radius on the corners so you'll want to do those first with a drill bit or hole saw, then cut the straight sections with the saw.