I’m already filing taxes in Portugal due to income from investments, but that is as a non tax resident - I only need to report Portuguese sourced income.
You’re right, filing as NHR does incur a higher paperwork (and mental) burden - you need to report your worldwide income to Portugal, and check that there are no gotchas which might cause currently untaxed income to be taxed.
I consulted my international tax expert (ChatGPT 4 
) and it walked me through these cases. Given there is no immediate plan to move to PT, I’m leaning heavily towards not going for NHR.