I know the OP said he had a ways to go before making this move, but I would caution those ready to move to a foreign country to hire an international tax firm and a residency/citizenship attorney before doing so. This forum is not the place to seek tax and residency advice. For example:
Residency for Portugal Income Tax
Residents of Portugal must pay taxes on worldwide income.
You are officially a resident if you spend 183 days or more in Portugal over a 12 month period, or maintain an abode. An abode can be described as one’s home, habitation, residence, domicile, or place of dwelling. It does not mean your principal place of business. “Abode” has a domestic rather than a vocational meaning and does not mean the same as “tax home,” when it comes to Portugal income tax.
There are 6 categories of income that are taxable: Income, business and professional income, investment income, real estate income, increases in net worth and pensions.
Other Expat Taxes
There are a few additional expat taxes Portugal enforces:
Stamp tax of .5% to 20% on the transfer of property
For Portuguese residents, capital gains tax is assessed on only half the value of the property and the applicable tax rate is based on your individual income. For non-residents, capital gains tax is 25%.
Also, for Portugal residents, be aware since Portugal taxes your worldwide income of pensions, etc., the tax rate for 2021 on taxable income of 36,967 euros to 80,882 euros is 45%!!! For non-residents it is a flat 25%.
Not trying to be a wet blanket, but the grass is not always greener on the other side of the Atlantic.