You cannot force somebody to move to the US permanently against their will.
It's very kind of you thinking about her safety, but I think this is all waste of time and money. Plus whenever she renews visa, she'd have to flag an immigrant petition was filed. This could lower chances of tourist visa approval.
And if she somehow gets GC, she cannot have "maintenance visits". It's for living in the US. If she spent 9 months in the US and 3 in Ukraine in a typical year, that's one thing. If she spends 11 months in Ukraine and comes for a month to the US to leave again - that's inconsistent with LPR status.
Again, think worldwide taxes.