The whataboutism here is pretty strong and pretty stupid. Specifically the Ukrainians don't *think* their homeland is under attack, it is literally under attack by any possible definition of the word.
Further, internecine conflict is not at all comparable as attempting to dislodge a foreign invader. One would hope that in such a hypothetical situation, most of the violent extremists on both sides, while not exactly getting along, could at least see value in each others' tactics in removing a hostile foreign threat, though given how bad things have gotten here, one would have to assume that one side would have already been co-opted by the invaders against the other. But ideally you'd see the right-wing 'patriots' raiding in the countryside while the left wing 'radicals' make occupying the cities impossible.
That said, if shit ever got that bad in an internecine conflict within the US, there would have already been a complete breakdown of the rule of law and every possible bad thing would already be happening so your point is moot and stupid, as usual.