Barely any. Just Poland (my country), Czechia, Slovakia and technically Austria (for few hours).
I definitely want to go to Baltics (Lithuania/Latvia/Estonia), Belarus, Ukraine, Hungary and Austria in the relatively near future, but I haven't even explored my country that much, so it's also on my bucket list.
The biggest problem is that I don't really have anyone to travel with, so for most of my life I just didn't do that, and only recently (couple of years ago) I have started to do it, but still very rarely.
I've just had crisis when 28, lol. Don't remind me.