I think it's just best to wait and see. In a little over 24 hours we will likely know how tickets will be allocated and with that I expect information to be provided about the testing requirements. I'm hanging fire until such time.
I can't help but think, however, that the emphasis will be on the official package and testing information only provided for people who intend to travel in such a fashion. Equally, I can envisage some sort of prioritisation with match tickets towards official packages. The Portuguese government may yet allow independent travellers to attend the game but it will be discouraged and disincentivised.