The manual doesn't mention the raw-burst capture rate, but according to the web, both are 30 FPS, with ~0.5s pre-capture, so 15 images from prior to your shutter press, and on the R7, up to 2 seconds after shutter press until the buffer fills, giving you 75 shots over 2.5 seconds. I didn't see a buffer size/max capture count mentioned for the R8.

Note to get the image out of a raw-burst you need to use DPP, or extract it from the burst in camera, as the whole burst is one big file.

Not quite A9III performance, but it's a budget camera, and it sounds like Joel would be happier with the image count too.