Hello everyone,
It appears many european countries have been a bit slow to update their online pages regarding foreign visits. Many places are now open to tourists, however it is impossible to purchase tickets online or reserve dates for them, since the pages have not been updated. For many pages, they have a specific page/url that is in english (e.g. you'll see an \en\ in the url). Removing this will enable you to access the original/updated webpage of the country (it will be in the countries language, but just use google translate, I use chrome so there is usually an option to translate the entire page), and you should be able to book tickets/reserve tours now. If its not in the url, sometimes they will have a button in the top right of the webpage, usually different flags (the UKs for english). Make sure to click to the nations flag instead. In rare cases they have it set so they determine via your IP, so you can use a VPN for these sites.
Although despite all this, sometimes their webpages are broken (this seems to occur more with Eastern European countries than Western ones, probably covid locked and never updated both domestic and foreign), and you can't even book via email because they just tell you to book the tour in person. Hopefully these issues will resolve in the upcoming weeks, but just thought I'd share my experience for those looking to book a trip before the sites are updated.