You'd be guilt/tripped and pressured by your well meaning peers.
And the only upper limit on how much charity we can give is the number of hours we have free. This spirals out of control in some groups (e.g. some religious charitable organisations or orders)
The animal rights charity here has very different volunteers than a religious charity which has very different employees than you find at Red Cross or Habitat For Humanity stores here.
> unhoused people who can only stay in the shelter if they work at the store.
I believe that doesn't exist here in New Zealand. It worry be very difficult to run a charity that way here because employees and tenants have very strong legal rights. I don't know how you could structure it to work - maybe a religious organisation with homeless members of that religion?