Check what various countries say about transit or exit on most direct way. Only very few EU countries still do border controls (one such country is Slovakia - no entry without 72h test or fully vaccinated). However many you can enter without test, or they allow you to enter with test requiring qurantine except if you leave the country on the most direct way. So just book a flight to another country then where you want to stay - and move over the border to another one (which will not check).
Especially Netherlands is super lenient. I have some family members who cross two to three times per week Netherlands to Germany or back because they kinda live on both sides of the border. No single time since the beginning of the pandemic have they ever been stopped. Also the border was never actually closed. Austrian border to Germany was different - a) because Austria was stricter at some points in time (not now) b) you usually cross into Bavaria, and Bavaria has been the most strict state of Germany concerning border regulations.
For crossing into Germany there is a paper form if you cannot register online - many many people use it. No check on border, throw paper away instead of quarantining. There is one single problem - if you cross into another country and within 14 days test positive - they will likely fine you (but fines for such things arent too expensive in most countries).
And in 3-4 weeks I am sure inside Schengen all controls will be abolished. Many countries start talking about dropping the mask requirement except for sensitive places like hospital, doctor waiting room and so on in a couple of weeks when they reach 50% fully vaccinated.
50% vaccinated (22 days after first dose), plus those with previous infection - that seems enough to get the numbers down pretty quick - well plus more an more time spent outdoors now due to summer in Europe…
I am pretty sure as long as you are vaccinated, there will not be any restrictions inside Schengen again next winter. They are using many restrictions to kinda force people to vaccinate. Not vaccinated = second class citizen in the EU. Very clear now.
Italy however was super strict at borders, but also inside the country often moving around forbidden and controlled heavily. They now seem to be one of the first to open up for tourism however.