In Prague you can eat at kosher restaurants on Shabbos.
In Berlin, Vienna, Budapest you can find home hospitality.
In Poland (and all of them) there's Chabad.
You can also go to retaurant for shabbat meals in Vienna and Budapest. I think also Berlin, but not sure.
I had shabbat meals recently at Alef Alef in Vienna, food was excellent and right next door to the shul.
Very pleasant experience, highly recommend. I thought it was reasonably priced @ EUR 35 all-in including salads, fish, soup, main, desserts, wine, soft drinks etc