I don't know why people think it's not possible to fire people in the EU, but it is and it's a normal thing. It just costs some money.
There is a process to firing. EVEN in the US there is a process of firing. The big lie is that most people are fed, is that in "right to work" states you have no legal recourse. You do, but not if you take the severance and sign your leave papers, because you panic right away. Something I didn't know either in the US.
The most important rule my (senior) friend once told me is to document everything, especially when your bosses make you do something that you feel uncomfortable with. Print emails if you have to and put them in a folder that you might never have to open if you're lucky.
You are technically still employed and paid but the company can refuse to let you step inside or connect to the network. You also can't work for another company without their agreement until the grace period is over.
It varies across Europe as well. Some countries, like Sweden, have more protections than others (no matter if union member or not), as an example. You cannot fire someone unless they demonstrably neglect their work duties and the firing overall needs to be objectively justified. Then the notice period depends on how long you've worked there, and more conditions I surely can't remember right now.
Compared to Spain that has "disciplinary dismissal" for example, where "insubordination" or "lack of discipline" could be enough to get you fired.
Exceptions can be made if justified, not dug into the details of how that works.
Your boss tells you to unpack a crate, you say no, boss tells you "f*ck off and never come back". Perfectly fine legally and you don't get any severance pay either.
There is some nuanced to this, as you have the right to refuse unreasonable requests and you are allowed to have a bad day if you have a longish good record etc etc.
For a knowledge worker it is more difficult to define what a reasonable order is and what constitutes insubordination, but the basic rules are the same.
However, another story is when mass layoff is going on. For example in Poland group of 9+ workers can be fired without any real reason. Downsizing! With 3-6 month notice period, of course.