I have not seen raw imagery to compare fusion vs max, but looking at what’s on mapillary, I don’t see the difference. I don’t know if Max uploads are frame captures or images, but the detail is still very low.
Fusion has been end of life for almost a year now, and still works ok. Knowing GoPro, I wouldn’t expect many new features for the Max.
If you are in the market for a standalone 360 camera for mapillary and don’t have the budget for an Insta360 Pro, I’d go for a Fusion