In Germany it’s legal for an employer to visit an employee. The employee is under no obligation to open the door, however.

As this article covers, it doesn’t really make sense to visit an employee, as the issue might not be visually apparent.

https://www.mdr.de/nachrichten/deutschland/gesellschaft/krankheit-kontrolle-arbeitgeber-erlaubt-100.html

Idk about Sweden, but in Germany middle management visited sick employees at their homes to check whether they were really sick.

https://www.tagesschau.de/wirtschaft/unternehmen/tesla-hausbesuche-krankschreibungen-100.html