THE RULES THAT APPLY in Europe
There is no shared set of European regulations for wild camping and bivouacking. Each country has its own rules.
As a rule of thumb, just remember that wild camping is generally prohibited (or at least strongly restricted) in most European countries.
However, some of them permit this practice, e.g. Sweden, Norway, Finland (where wild camping is fully authorised) and Scotland (except on some of its islands).
As for bivouacking, the rules in Europe are a little bit more flexible than they are for wild camping.
Once again, the rules for bivouacking are more relaxed in Scandinavia (Sweden, Norway and Finland).
These 3 countries have a right of way called the "Allemannsretten" law (literally "every man's right"), which is an ancient custom that allows everyone to enjoy nature.
In these countries, bivouacs (and wild camping) are allowed under one condition: you must stay more than 150 m from any dwelling and respect the local flora and fauna.
You can also bivouac in national parks.
As for private land, if it is cultivated land, you simply have to ask the permission of the landowner to pitch camp there.
In the Baltic states (Estonia, Latvia and Lithuania) bivouacking is generally permitted, like certain countries in Eastern Europe: Albania, Belarus, Bosnia-Herzegovina, Romania, Russia, Serbia, Slovakia and Slovenia.
As for Western Europe, the rules are stricter and vary depending on the country, or even the region (or locality) and may vary depending on the season.
Take Portugal, for example: wild camping and bivouacking are generally not permitted. However, they are tolerated outside the summer period... as long as you are discreet and do not camp on the beach.
It would be too long and too tedious to list what is permitted and prohibited, country by country.
As you can well imagine, there are many laws and their exceptions, as well as, sometimes, a certain form of tolerance towards wild camping (more rarely) and bivouacking (more often).
The best solution is to make inquiries when preparing your expedition to a particular country, and respect the "good practices" mentioned above, which apply to France, but which are also universally accepted commonsense rules that protect nature, yourself and other people.