Without knowing where you’re located, Food Not Bombs has locations all over. Otherwise, find local groups that are doing mutual aid work and join them. Most of that type of work is being done on a small scale local level, so it would be hard to say.

If you’re looking specifically for trans activism, The Transexual Menace came back and already organized a protest at Stonewall last week or so, and they have plans to organize a lot more across the US. They’re US based, so I suppose it may not be helpful if you aren’t in the US