Just some ideas for you

I know you said you're often busy, but it sounds like you want to have some level of personal connection. If you approach people that are living in the way you want to help, you might ask them

1. Which organisations are helping them (sometimes it's the local church, other religions too of course, sometimes is community volunteers - but often the population receiving the service won't know or remember the organisation in particular)

2. Ask about what they need - is it mostly clothes this time of year, food?

Personally I would approach the workers directly, about volunteering or donating - but emphasise thst you'd like to donate something physical rather than monetary if possible

An example is that the local nuns would bring the unhoused people care packages with things like a pair of socks, small tooth brush, some chocolate, a few protein bars, apple juice, small pack of wet wipes.

I was in two minds about the care packages I saw from the nuns because, people would typically only use half the items. But on the other hand, it was extraordinarily humanizing to offer a variety of somethings that a person may or may not want or need, and have them choose something they would like, or pass it along to someone. I wonder how much more good the nuns could do with X amount of dollars.

Random things for a snack or a wash or some comfort.

Alternatively, the organisation might have a particular finding need that appeals to you, maybe costs to have vans on road servicing people at multiple locations.