There are quite a number of threads here on the PE/fund option, which can also mean open-ended funds. Suggest you read those, this one being the primary https://community.nomadgate.com/t/portugal-gv-fund-comparison plus others on apostille and PFIC/tax requirements for american citizens. (You might have other passports but I imagine since you are a US citizen all the US citizen stuff will apply.) The PE funds have to meet certain requirements and be approved. (The RE funds are really PE funds by another name.)
No one here really knows much of anything about the capital transfer option, it comes up from time to time and we get nothing, other than it involves a transfer into a Portuguese bank/broker since a Portuguese firm has to attest to the details of your transfer - simply buying 1.5mm of Portuguese stocks from your Chase account doesn’t cut it. We’d note that it seems clear it has to involve investments in Portuguese assets in one form or another. Though if you’re going to do that then you may as well buy one of the open ended funds with the lesser amounts and not fret about it.