You can literally go outside and talk to people. There's no moat around dating apps. Human beings continue to exist in meatspace. I am yet to see a dating app contract that prevents you from being casually approached by strangers. Heck matchmakers still exist.
You can't . If you talk to modern city people the way you casually said 'hi' to strangers in the 90s , at best you 'll end up in a tiktok branded as a creepy person
I've done this a few times over the last few days alone (in Seattle no less, a city infamous for being antisocial - though I'm willing to accept some were tourists for the 4th).
IME, people are actually starved for human interaction.
It's an common thing to see someone complaining about a "creep" (quotes as in, I'm quoting them) because someone tried to hit up on them and so on.
In today world, what you're speaking is at best dangerous.