Yes, this is a good idea. You could also focus on the community-building aspect: these are our neighbors, capitalism has done huge violence to them, and we need to take care of each other because nobody else will. Whatever aid you focus on will likely be useful for more people than just the unhoused, which is ahain good community building.
Choose the right community to start in, too. Suburbsn rich crackerville will probably dehumanize the people you're helping and see it as harmful. I wouldn't do my first action there.
Tie your work to a larger project as well. Build a list of supporters with contact info so you can push a local electoral campaign, hold rallies to pressure politicians, etc. This will help justify and offset costs, as aid $$$ quickly adds up and you will need donations and all opportunities to build power.
Be ready to board a plane and get out early enough.
The first is about having money. Easier said than done, of course. If you want to be particularly secure, you'd consider having enough gold for it, as it's an inflation hedge and I would not be surprised if hyperinflation coincided with these things. Yes I know that buying gold sounds silly lol.
The second is about deciding when to fight and when to run. Not easy and a personal decision, but people who stay too long if we lose will be in a bad situation.