Write in: Green.
Puerto Rico will presumably not elect politicians from the Democratic or Republican party, but rather their very own local parties (PPD and PNP respectively, though in 2020 there was a huge third party wave which reminds me a bit of Spain 2015).
Presidentially PR will vote for Democrats but it will send essencially 4 independents to the House of Representatives and 2 independents to the Senate.
In addition to the point mentioned elsewhere that the PPD and PNP politicians affiliate with national parties (all PPD politicians are Democrats; PNP politicians are split about 50-50), the main political divide between the PPD and the PNP is based on statehood. Once statehood is a fait accompli, I doubt those organizations would survive in the same form; likely the PNP would fall apart as seeking statehood is basically all that holds it together currently, and you'd end up with the Republicans (the right wing of the PNP) and the PPD-Democrats (union of the PPD and the left wing of the PNP) as the two main parties.
Definitely possible for reform/anti-system parties to occasionally have success at the state level, but they would probably not have much influence in national politics (e.g., in Congressional elections) without actually displacing either the PPD-Democrats or the Republicans (likely the latter, since the Republicans would be a permanent minority party in PR anyway).