His offer for Ukraine is surrender. Ukraine would need to give up the 4 oblasts that Russia considers part of Russia, including their 2nd and 3rd largest cities.
Both 2nd and 3rd largest cities of Ukraine are outside of borders of 5 contested regions.
The funny thing is that nearly half of transnistrians already have Russian citizenship. Even the funnier thing is that nearly quarter of transnistrians hold Ukrainian passports and have by far higher chances to be drafted during upcoming mobilization. And the funniest thing is that some of them have both citizenships simultaneously effectively meaning that they can choose the side to be drafted for.
Only abovementioned 5 regions had referendums and therefore fall into "Russia considers part of Russia" category as they are really treated as Russian regions by Russian law. Any other regions of Ukraine are not, at least currently.