The best case solution is that services stop requiring ID, problem solved, but ID requirements are just getting worse every year. Second best case is if the UN would issue stateless IDs for people who can't get documents from their country of birth/residence, but this doesn't exist (Nansen passports were discontinued in the 1950s with no replacement). Third best case, a NGO issues substitute IDs which are accepted on a case-by-case basis, but this also doesn't exist. Clearly a "DIY ID" is unlikely to be accepted in real life, which makes the self-declaration more of a philosophical thing than a practical use case.

Tipped you 100 sats.

In the first paragraph of the website/article:

"ID documents do more harm than good and should not be seen as a solution for trust or authentication. Many economic and social interactions can be done anonymously. For other situations, trust can be achieved by simply saying your (self-chosen) name, using a web-of-trust, word-of-mouth reputation, vouches, memberships, escrows or cash deposits, and authentication can be achieved by using a password, cryptographic key pair (e.g. PGP, Monero) or physical key or code (such as house keys or a safe code)."

However, if a service almost universally demands ID (most jobs, housing, healthcare), it would be better if it would accept something that you can earn or make yourself, rather than something that depends 100% on your circumstances of birth (even citizenship by investment requires documents from your birth country, which your birth country may refuse to issue).