5dmkii to a mirrorless Canon

I went from the 5DII straight to the EOS R, having briefly considered the RP without having actually handled it. My main consideration was image quality (the sensor for the R is based on that for the 5DIV, that for the RP is based on the 6DII's). The very nice match-triangles focus aid is missing from the RP and the R has a better viewfinder and general build. The batteries from your 5DII will fit the R if you have any spare and they're still working. Budget for a spare battery for the RP as it uses the same small battery as the top EOS M cameras.

The RP has automated focus stacking for your close-up work. You can still focus stack with the R, but a focussing slide and a bit of mathematics would help.

This chart, https://photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205D%20Mark%20II,Canon%20EOS%20R,Canon%20EOS%20RP compares the dynamic ranges of the Canon models; it's easy to add your Fuji if it doesn't show it.

The RP has about 8% more linear resolution than your 5DII, the R has about 16%. It's noticeable; but not as noticeable as the improvement in the shadows (much less banding).

Handling and controls will be different from a DSLR. Canon rethought and refined mirrorless controls to take full advantage of the touch screen over several generations of the EOS M. They can take some learning (especially as your Fuji has controls even more like a film camera than those of your 5DII) but they're very good once you stop expecting a mirrorless camera to work just like a DSLR.

All my EF lenses seem to work better on the EOS R, mainly because of the improved AF and also because of the improved sensor.