Organizing politically.

While private ownership of production is in place, there's no amount of boycott we could reasonably do too make changes. As you've noted, it would end up starving people and making them homeless.

On the lowest effort end. Using the power we currently have; we should vote for the least fascist of the two party members. This will not save us, but it will slow the decay and give time to others who are more actively working to solve the problem.

People with more time and effort, should organize. Push for getting rid of the first past the post voting systems and replacing them with less broken voting systems. Try to create leftist candidates and get them elected locally. Spread leftist ideology to public.