My wife and I do real estate shots, and I cannot see where a prime is helpful. You need flexibility as each room is different in size and shape. I would get a very good zoom lens.
If you have FF, then a 16-35 or the Sigma 12-24.
If you have a crop, then 10-22, 10-18, Tokina 11-16 (careful with fringing on the edges of the frame), or the Sigma 8-16 (just recently acquired).
You aren't going to want to constantly change lenses (time, wear and tear, etc), so either you go with a prime UWA and do alot of post cropping, or get a more versatile zoom, shoot a bit wide, but then have the flexibility of framing for each room.
I am sure some might shoot with primes, but they perhaps also have multiple bodies that are already mounted with primes.
Also, we recently added the AD200 strobes to the collection, and they act as very bright floor lamps for us, or a large softbox behind us. We strategically place these in the scene to light upwards (power at 1/32 or so), or at a wall behind us, and control with the X1T. This is a very portable and versatile kit for real estate shots now.
Here is a thought, use your primes in your own house...