Your note about flash is exactly why I liked my M5 over the M6. If I mount an EVF, my Phottix triggers can't mount. Our son just bought my Canon M5 a month ago. I almost bought another one, I liked it so much !! But I used it most for hiking and some video for-the-record stuff.I really want the m5 Mark II as a poor man's 7d2 upgrade. I would have pulled the trigger already on the m6 mark ii but i want to be able to use external flash.
I figured my EOS R with a smaller lens could fit the same bill, or maybe even an RP too, once those used prices dip more. Either way, I think the M5 is a wonderful camera.