An F-35 doesn't need to be faster than an SU-35 when it has triple the radar lock on distance and missiles the SU can't outrun. The thing has a radar cross-section of a US 25¢ coin and can see beyond the horizon on radar, the Russian planes would be dead before they could react to it. It's such a comically overpowered plane that talking about it makes one sound like a kid at a playground making up rules for his action figure in a make believe fight.
I think you oversell the F35 stealth. It really depend on the angle and speed of the plane, and the age of the radar (fwih the radar signature of a us coin was true in 2014, but optics and radars have improved too, especially recently, and especially thank to the Ukraine drone war feedback). The future seems to be fighter + cheaper drones with similar radar signature rather than full stealth. Which might be easier to do with the small f35 signature for sure.
But every military is aware that the plan to go full fox-3 (+ stealth) might die in the next decade, and we might be back to FOX-2 / dogfighting. Is it likely? Not really, but drone and AI change the battlefield to much to be sure of anything.
I think you're giving the F-35 a lot of unjustified credit. For one, Russian air doctrine has long fielded interchangeable radar/IR homing seekers specifically to target American stealth platforms. If your F-35 is afterburning so it can match an Su-35's supercruise speed, they can get smacked by an R-77 from BVR by a Russian jet just as easily as an AIM-120 could crush the Sukhoi. Radar stealth is not a panacea in the EOTS era, and the F-35's side/rear aspect stealth is not enough to make it invisible at every angle.
Furthermore, as much as I love a slick single-engine fighter, the F-35 is still fundamentally designed to operate in contested airspace. Canada, if they operated the jet for the next 50 years, would likely never have to use it for it's intended joint strike purpose. Unless you habitually molest the borders of other nations, the F-35 is not a purchase that makes a whole lot of sense to taxpayers. If the F-35 was truly "comically overpowered" then Congress wouldn't be asking to restart the F-22 production line, now would they?
> For one, Russian air doctrine has long fielded interchangeable radar/IR homing seekers specifically to target American stealth platforms. […]
Is that a demonstrated capability, or a claimed one? Because if there's one thing the war in Ukraine has shown, it's that Russia seriously overpromised on the performance of its high-tech hardware.
Congress wants to keep the A-10 Warthog flying even though the Air Force desperately wants to be rid of it because it's a good jobs program, there are considerations outside of battlefield prowess that go into their thinking. Not to completely dismiss their opinions because they probably have more information than we do, but their world is not warfare.
Even giving the Russians every capability that they claim to have, it is questionable if they can even keep producing much of the high end of their technology with the sanctions leveled against them. Without Western components they are unable to manufacture a decent range of their good stuff.