I've still got my M6 II and lenses, but I've taken to using R kit mostly for travel these days.
I've a lot of kit with all sorts of options, but my main travel kit is, or is a subset of, R8 plus 24-240, R50 plus 18-150, 10-20 L, 10-18 RF-S if R50 only, 24mm f1.8. (Lots of other lenses available to me that I sometimes take instead or as well). I can get all this (only 1 of the wideangles) plus a couple of polarisers and a decent number of batteries (5 spares) in a LowePro Nova 180 bag, which is pretty unobtrusive and easy to carry.
For me, the R50 is the standout model in the current crop range for my needs. It's a LOT smaller than the R7, and still a fair bit smaller and lighter than the R10
R50 is 6mm narrower, 2mm less "tall", and 14.5mm less "deep" (front to back - almost entirely due to the much shallower grip) - than R10 - so really the cameras are effectively the same "size" once a lens is fitted (that protrudes beyond the grip). R50 is also 54g lighter (which is fairly insignificant).
R50 lacks a few of the controls, dials & joystick of the R10, including an "AF On" button. It also only has (according specs) 6 custom functions vs 18 custom functions plus button & dial customization on R10 - so quite a lot more basic.
So, it really depends on what the OP wants it for and what lenses are to be used - if shooting moving subjects, the the AF ON button might be important if wanting to use dual button BBF. If shooting with larger/longer/heavier lenses then the deeper grip might be important. I could imagine that a heavier lens like RF 24-240 might be more unwieldy on R50 ? Another thing to consider (depending on use) is that R50 only supports UHS-I and has a MUCH smaller buffer than even R10, so R50 will be very limiting for any kind of fast moving shooting (wildlife, birds, sport etc).
For me, the extra "size" of the R10 compared to R50 or M5/M50 is almost entirely due to the grip depth (as above, the other dimensions are almost the same, and the weights are almost the same), but it doesn't take away any of the camera's portability or packabilty (in a bag) once a lens is fitted - and the larger grip adds a lot to the camera's usability with larger or heavier lenses.
; it doesn't have the horrible joystick, something I absolutely hate
Are you referring to the more "traditional" R10 joystick, or the unusual one that R7 has ?
; and the auto subject sensing AF is much better for travel for me than the R10 or R7 systems.
Which is easy to get around because R10 & R7 have Custom modes (which R50 doesn't) so a subject detection group of settings (like servo, faster shutter speeds, higher ISO etc) can be set to C1 or C2 for times when it is required and otherwise just use a "normal" mode (like Av) with One Shot and single AF point.
And much more basic.
And the limitations of the camera don't trouble me in the slightest for travel.
It depends what the travel involves - if it includes things like a wildlife safari, then the R50 may not cut it. If it is just friends, family, and street & landscape, then it might be perfectly fine. Personally I saw sensor cleaning on a mirrorless camera with an exposed sensor as being quite important.
In manual mode, there's a dial for shutter speed, the lens ring for aperture, and a button to access ISO, which works well for me.
The R50 and the 2 RF-S lenses is nearly as compact as M6 II and 11-22 and 18-150. Yes, a few less pixels, but video is good and I've come to really enjoy this little camera, certainly more than my M50.
The R50 is certainly closer to the M6 ii is size (mostly because of it's small grip), but quite different to M6 ii in that it only has 1 dial vs 3 (on the camera).
This is a very personal preference thing though - it is like the old EVF vs no EVF debate. I would (and did) gladly pay the extra for the R10 because (to me) it offers a LOT more camera. To anyone used to a basic camera like a M100 or basic Rebel, the R50 would be OK, but to anyone coming from a more "performance" orientated camera, I suspect it might be lacking. There is just too much "missing" from R50 IMO for anyone coming from M6 ii (or even M5 /M6).
Perhaps an R8 + RF 24-105 STM might be one to consider ? It is generally better than any of them in most respects - except on price.