I’m sure you’re aware that FAANG take extreme measures to prevent union representation or membership in their companies.

Obviously you’re your own person, I recognise that we should unionise, but selfishly I would be concerned with potential blowback; maybe you don’t pass probation somehow.

If you’re intent on doing this, I heard decent things about prospect: https://prospect.org.uk/tech-workers/

In Sweden it would be unionen, but unions are usually country dependent (for obvious reasons)