Hello! Unfortunately, I can't tell you how to cross the border, for example, as an EU citizen. As a citizen of the Russian Federation, I entered Belarus with my internal passport without any security checks (except for the security check at the train station as part of terrorism prevention in Moscow). Russia and Belarus have a union state treaty (we can travel from Russia to Belarus as EU citizens within the EU). I haven't heard of any discussions about any difficulties with entering Belarus from the EU side. I'm not an expert on this matter.