"Hola" is mostly fine, and totally fits with the LTC influx.
"What's up" and "How's biz" give me social anxiety IRL when used as greetings, because I feel pressure to respond to someone who likely doesn't care about my answer but still wants me to give it as a segue into them talking about whatever they wanted to verbally interrupt me with. They don't evoke "hi" to me. It'd be a lot easier to use them as greetings if they weren't a problem IRL now.
Are other regional hellos, like salut, ni hao, howdy, and konnichiwa still in circulation?
In addition to more neutral / casual hellos, I'd love some phrases that I can use to denote the emotion behind the type of hello, like...
What can I say as a greeting when I'm really excited to see someone? Equivalent to a squeaky "hi!"
When I'm disgusted / uncomfortable / awkward / frightened / sad to greet someone? Like a quiet "hey."