Would the law they passed last month qualify as self-identification? The relevant legal text (roughly translated by me) says:

A person who has reached the age of 16 shall, upon application, have it established that the person has a gender other than that shown in the population register if [...] the gender shown in the population register does not correspond to the person's perceived gender identity, and it can be assumed that the person will live in this gender identity for the foreseeable future.

See also:
https://www.riksdagen.se/en/news/articles/2024/apr/17/it-will-be-easier-to-change-gender_cmsf772fcc0-2851-4007-a2d2-0712267e44c5en/

https://www.riksdagen.se/sv/dokument-och-lagar/dokument/svensk-forfattningssamling/lag-2024238-om-faststallande-av-kon-i-vissa_sfs-2024-238/