Thinking of A7 IV over R6 II because of lenses... help?

For context, I last shot with 5D Mark IV - all L glass and a couple Sigma Art lenses. Was shooting professionally, but not anymore. I definitely like Canon. Sold it all so effectively starting from scratch.

I am planning 99% stills photography. Mostly photos of my dog when we're out on big adventures - so I also am putting a bit more value on size+weight (but not a dealbreaker)

Been debating between the A7 IV and the R6 Mark II and it seems they are effectively interchangeable depending on where you put value. I think I would absolutely be happier with the canon BODY, but the lens situation is annoying.

Looking at Sony, I'm imagining my workhorse lens would probably be the Tamron 28-75 2.8. But this isn't even available on any Canon mount. The RF 24-70 is big and heavy and expensive. The RF 70-200 F4 looks really nice and compact - I liked my EF version but did always hate how long it was (for packing in bag and such)... but then there is also the Tamron 70-180, and in a 2.8 variant. And beyond those two options, there simply a lot more options on the E mount. If I need a specifically smaller+lighter lens, there's options for that. If I'm just doing local walkaround photography I could go get a great 50mm prime or similar. The EF-RF adapter makes things clunky and bigger+marginally heavier. Seems like it would be an annoyance.

Sooo what do you guys think? I *want* to want the canon, but think that with the current RF lenses being almost exclusively big+heavy+expensive (or cheaper but much lower quality), the Sony camera makes the most sense BECAUSE of the lenses. Anyone able to convince me otherwise?

Why not consider APS-C or MFT if you are just taking pics of your dog on adventures?

I actually have the A6600 and generally don't enjoy using it. I find it... TOO compact? The controls are difficult to work with and I miss things like joystick, buttons that don't get pressed by accident... glove-friendly... etc. But the AF is great, which at least at time of buying, the other APS-C camera bodies definitely had inferior AF - especially when talking about animal eye AF and such.

And to be fair, APS-C might still be a viable option. It definitely wins for the smaller+lighter.

And I do personally prefer the larger apertures with shallower DOF, which is harder on APS-C. Actually have the Sigma 18-50 which is great to work with but is basically a 24-70 F4, when I loved using the FF f2.8 zoom... and wider aperture primes.