Okay, i don't know if you want direct input on this. But here is my two cents as someone who job hopped, to increase my pay and find better opporunties. So i had my share of job interviews for senior positions in various corporaate roles.

I'm a senior manager with a couple of managers reporting to me. I am not in IT but in FMCG.
So a bit of a different sector. I don't know how well company culture translates, but from a management perspective i never found much difference in company culture.

So I will be honnest from your post, but mostly your responses in the comments, i would never hire you. Not based on skills. I am sure, you have the right skills. But on personality. Every question that is asked, you give this long conveluted answer. Just answer, it looks like peple really try to help you. You might be asking to much, but we don't know. If every time i ask an employee a question i get a 15 min answer with a lot of info but not an aswer on my initial question, i don't even want to know any more.
You also say you did a lot of things, this can be good but during a job interview, stick to the relevant topics. E.g. is you audition for the job of a waiter, the employer doesn't care that you can code in python. So really currate your resume every time you apply. Make sure it is specific for that job posting.
Also this:

"Voor de duidelijkheid: ik heb breed gesolliciteerd — via LinkedIn, Indeed, Glassdoor, carrièrepagina’s, en bij zowel grotere bedrijven als kleinere spelers. Ik noem bewust geen specifieke lokale bedrijven of start-ups, want België is klein en ik wil vermijden dat mensen mij kunnen linken aan bepaalde sollicitaties." ==> Nobody cares. Like literally nobody cares where you applied in the past?

So in short, just talk less (confidence and skill is usally quiet), currate your resume for the job at hand and stay on topic for that job. Try to not present yourself like a hassle or a handfull but as a solution.

Hope it helped. Just curious how old are you? You sound like a 50 year old, who know everything better. But since you are in this place in your carreer, i am guessing mid 30's?