Do you believe that the people have Donbas have a right to self-determination and representation in government, and that that right would include having some possible roadmap to joining Russia
Of course. They just don’t have a right to drag the rest of Ukraine into Russia at the same time. On principle, I support pretty much any separatist movement on the grounds of “why should I care if a country’s capitalist class loses some of its economic base?”
should they be forced to either go along with whatever the new government wanted or abandon their homes and flee the country?
No, but if that’s what was happening we could all then be criticizing a peacetime government for acting injustice upon segments of its population, instead of advocating for an end to a war. The idea that a country should intervene militarily in order to “save” a group of people isn’t one based on honest, good-faith altruism on the part of the country that wants to intervene, if it were, then wouldn’t we be in a constant state of war everywhere? (Since there’s pretty much at least one oppressed group in every country worldwide at least one other country could claim a right to “protect” them based on shared heritage or language.)
Just because Russia (might) have the military capability to do so when all these other countries might not doesn’t mean they should.