There seem to be four funds that invest in a broad portfolio of Portuguese equities. I’d strongly advise calling the funds/depositaries to check the eligibility for US persons (particularly BPI).
BPI Portugal
Initial fee: 0%
Annual fee: 1.195%
AUM: £41.9m
1y/3y/5y total return pa: 12.02%/12.33%/8.96%
US eligible?: Common wisdom from several years ago was No, but I’m not aware anyone has actually asked them in recent years
IMGA Class R
Initial fee: 0%
Annual fee: 2.175%
AUM: £208.0m
1y/3y/5y total return pa: 10.20%/10.04%/6.28%
US eligible?: Yes according to various people on Nomadgate
Optimize Portugal Global Opportunities
Initial fee: 1%
Annual fee: 1.8%
AUM: £19.8m
1y/3y/5y total return: 8.95%/na/na
US eligible?: Yes according to Open Investment Fund options for US Citizen
Sixty Degrees Ações Portugal R
Initial fee: 2%
Annual fee: 1.75%
AUM: £8.8m
1y/3y/5y total return: 9.78%/na/na
US eligible?: Yes according to Open Investment Fund options for US Citizen
Links below
https://markets.ft.com/data/funds/tearsheet/summary?s=PTYPIGLM0000:EUR
https://markets.ft.com/data/funds/tearsheet/summary?s=PTIG1DHM0003:EUR
https://markets.ft.com/data/funds/tearsheet/summary?s=PTOPZWHM0007:EUR
https://markets.ft.com/data/funds/tearsheet/holdings?s=PTSXYIHM0002:EUR
https://www.imga.pt/en/mutual-funds/equity/imga-aÇÕes-portugal
https://optimize.pt/en/investment-funds/portugal-golden-opportunities/