Personal: Choose FOSS first, and contribute some of your time and money towards projects that align with solarpunk ideals. Get into self-hosting and eventually perhaps community-hosting for local organizations or neighborhoods or someting like that. Find your local makerspace and meet up with tinkerers there and find common community projects to work on.
Work: At my work, my small team of devs are currently trying to break out of an otherwise heavily Microsoft-based ecosystem. So far we've gone from a general hostility towards FOSS to being allowed to run things on bare metal Linix servers instead of Azure, and I my request for a Linux laptop is approved (though still waiting on them to learn how to install Linux or something?). As part of a research project we are trying out FOSS alternatives to Microsoft products in hopes of creating interest and success stories. We are also in that project going to open source some of our internal development. I've also challenged my bosses on the heavy use of products from a single major tech company.