Anything with a Sony sensor
That said, the Ra is no slouch, but I went through the process recently of thinking about mirrorless cameras. In the end, I decided on a dedicated astro camera.
Why? Because a Canon Ra isn't cheap. Neither are the great astro-cameras of course, but the Ra can't be cooled down. For that sort of money, I'd want a really excellent astro camera. That was the biggest thing that swayed me. Being able to cool the sensor not only means ultimate noise control, but more importantly, means darks can be taken at a different time to the lights. I no longer have to stay out in the field an extra hour or so (minimum) to collect darks. I can do it during the day whenever I want.
So just under two weeks ago, I changes from a Canon 5D IV to an ASI 2600MC, and have been very happy with it so far (there's definitely a learning curve to using an astro camera)
Sorry to throw that in, but give it a thought anyway