As I understand it, by being more massive this black hole has roughly the same angular size in the sky as Sag A* at the center of our galaxy, but none of the dusty foreground in the way so we get a clearer vantage point.

They did. M87* was the widely publicised "first" photo, but they also got images of Sagittarius A* (the supermassive black hole at the center of our galaxy).

The difficulties with Sgr A* are twofold:

- The black hole moves too much during an observation (because it's much closer, and parallax is a thing)

- Sgr A* is much smaller than M87* by mass, so even though it's much closer, the angular diameter is almost the same, and the accretion disk is dimmer.