Re: Rambam and the oaths. I don’t think this has the weight you imply. This is a letter to a subjugated community under duress, and he is trying to stop them from a rebellion that will surely lead to their full destruction. How would Rambam react to a viable Jewish state in EY remains unresolved from that, I think.
We might infer Rambam’s view on desirability of modern Israel in EY here: he asks you to consider the world to be balanced in mitzvos and aveiros and yours to be a deciding factor, so presumably he would just sum up mitzvos v. aveiros in EY to make a decision. I don’t know how to calculate this precisely, but it seems that proportion of Jews keeping shabbat, yomim tovim, kashrut, marrying Jews is way higher than in US or Ukraine for the lst 100 years.