Completely anecdotal story, me and a friend had completely different experiences going to Portugal. We're both Brazilians so language, food, culture aren't barriers, he's very talkative and would joke and try to interact with random people in the street or restaurants. He had a terrible experience, hated the country, vowed to never come back, said he wasn't welcomed anywhere, people were rude, even waitresses.

I'm more of a "talk when talk is needed" person but still social. i don't really interact with strangers in the street and I assume business social interactions (like restaurants) are just that, business, so I'm polite but i'm not going to crack a joke with someone i've never seen before and will likely never see again. My experience was the complete opposite, loved Portugal, would easily move there if salaries weren't shit, people were nice, i felt welcomed anywhere i went, might have been the only place outside of Brazil i have really felt at home.

I think its important to NOT BE RUDE with the random people you meet in the street but I also see no reason so strike a conversation with them. If I happen to see something that picks up my interest, like a band shirt, book i like or something like that, i might bring it up if we're going to stay in the same place for long, but starting a conversation out of nowhere just isn't a thing for me.