Asklemmy

Depends on your priorities and goals.

Do you want to feel good momentarily for doing something good? Get some interpersonal gratitude? Then yes.

Do you want to reduce homelessness in your community? There are probably local projects for that, where your money will be used more effectively.

Do you want to be altruistic, helping people in need and want your money to be used as effectively as possible? Look into reputable charities (like Helen Keller Intl, preventing child blindness and death with Vitamin A is hella cost effective) or funds. I looked into the same thing some time ago and stumbled upon givewell.org. They evaluate charities based on a number of ratings and choose the most effective ones for their funds. Been donating through them monthly for a year now. Also, it is tax deductible so i get almost half of it back.

My opinion is no. They can then use it to buy drugs or alcohol, which is unfortunately likely.

Maybe you could donate to some homeless shelter?
Or maybe, you could try asking if you could buy them some food instead.

donate to local nonprofits

I don't because I'm concerned that they would use my generous gift to just go out and buy drugs. And that may be cruel of me. But I would rather donate to a charity that feeds the homeless, such as a soup kitchen. Or if I see somebody that would look hungry, I would rather buy them a meal directly than give them the money for it.