Go figure out what it’s like to be arrested in your country and use that to make your decision.

In America if you don’t have an id they’ll fingerprint you when you’re arrested (they’ll do this anyway if your prints aren’t on file) and compare your booking photo and fingerprints to their database to see if you’re a match. If they go around after the protest and your cars tag comes back to you then they’ll impound it and you’ll be faced with civil asset forfeiture, so don’t drive to the protest. They can hold you for some amount of time depending on the charges during which you will get to make minimum one phone call. I recommend you have a designated person whose number you know who will actually pick up random numbers and who isnt enrolled in any do not call or anti spam registry (some jurisdictions have their outgoing line from holding on those lists so it never even rings through for the person). You will need to make sure your phone contact gets you a lawyer and a bail bondsman post haste. You can be deprived of medical care the police aren’t aware of or simply don’t believe you about. Law enforcement maintains a database of people and you can be assured your entry will be updated to reflect their opinion of you. Be aware in any future interactions with cops after your post protest experience that you may need to affect obeisance because their system has you tagged as Hostile to Law Enforcement.