If you travel abroad solo … a good way to meet locals is to book local tours (food tours, adventure stuff) where the guides tend to be locals. I’ve been on a few of these types of outings where solo travelers were also there. Nice people. Plus you can chat up the guide and get some insider info on cool night time stuff to do and possibly score a friend to show you around for a bit (of course, be a bit cautious but generally tour guides are pretty fucking cool people. Had a food tour guide in Lisbon who was a surfing, bass playing PhD candidate who lived in the Al Falma - she was pretty fucking sexy too - even my wife thought so). Plus you look brave and confident if you’re able to travel abroad by yourself. Also, look into staying at a hostel or something where other small(er) groups of travelers tend to congregate.
Movies are the perfect solo outing. Who the fuck wants to talk during a movie? Plus, no one to snag your snacks - A+ number one time.
When my wife is working on the weekends (about once a month) I’ll treat myself to lunch at a local place (especially if I’m busy doing work around the house and don’t want to devote more than an hour away). I tend to sit at the bar so as to not take up a table best utilized by more than one person. But I’ve had zero issues with any of this - I could give a fuck if anyone thinks it’s weird tbh. Sometimes I strike up a convo with another solo eater or I just keep to myself and read a book on my phone or people watch and come up with back stories for the people in the restaurant or just talk to w/e cute waitress is tending. A little harmless flirting never hurt anyone (especially when they view it as harmless since every local place knows my wife and I).
But, nah, I don’t think there’s anything wrong with this as long as like you’re not a creepy bloke.