[tpxl]

You don't have to divulge company secrets, talk about public knowledge from the company, ie frontend design (React, Angular, whatever), any outer facing APIs (REST, SOAP, RabbitMQ, whatever) and stuff that is public knowledge, ie. stuff from blog posts or general knowledge (like GCP/AWS/...).

Besides that, you can always just not say what company something occurred at or be vague enough.

[stnmtn]

More the part where you're contracted on trial for a week. How do you do that will a fulltime job?

[version_five]

You have to quit and start the job at some point. You might also hate it after a week. The trial at least gives both sides a lower risk way to test each other out. You could take a weeks vacation, or surely would be able to negotiate a week to do real trial work before you are forced to quit your job.

This is actually common in some trades, for example cooking / baking, and makes way more sense than interviews for both sides to decide if they want to continue working together.