based on proximity, Indonesia would be a better choice in my mind. That's pretty awesome that you are going to do that!
It's kind of strange what you describe about the Russians in Phuket. Years ago when I was there it seemed like almost every business had Russian language on their business but now that is all but completely disappeared.
We intend to sail to Thailand after Indonesia, but I think indo will keep us busy for a year or more. That's very interesting that Russian is not so prevalent now in Phuket. I wonder why, aside from covid 19 of course.