Is Portugal a cash only (or preferred) country?

Cards most everywhere - if you need cash, get it from a bank ATM, not Euronet.

I came across 1 or 2 places that wanted cash for small purchases, but that was two years ago.

I always carry cash. I’d rather have it and not need it than not have it and need it.

If I don’t have leftover cash from a previous trip I’ll order some from Wells Fargo while I’m home.

Pretty much credit cards everywhere. I do keep a stash of small bills and 1 and 2 euro coins to use as tips or for a small purchase, especially from a market stall. Echo the comments about getting cash from bank ATMs not EuroNet (they have higher fees).
Enjoy your trip there!

In 2023 we came across a few places that only accepted cash, so you will need some. For example: the boat ride to Almourol castle, a bar and a museum in Coimbra, the funicular in Nazaré.

Most places took cards.

Some small family run restaurants only took cash when I was there last year. Twice I had to leave and find the nearest ATM to get cash to pay the bill.

You, as others are saying, can get by with mostly card. I did specifically look for some small restaurants, Tascas as they are called, that are usually family run, and a good share of them cash only, so having some cash on hand is a good ideas. Plus, the little stands that sell Ginjinha (a cherry liquor) are mostly cash operations.

Like most European countries, I have 50-100 euro on me, if I need it I have it, if not, it is there for the next trip.

Be careful when you see a place accepting credit cards. Some places only take Portuguese credit cards. Always ask. I had to go find an ATM twice.

Thank you, everyone, for your helpful advice. 💐