A quick round-up of the groups I know of organizing in Portland and their public channels:
50501 Portland is rebranding to No Kings Portland, but they've been a consistent group of organizers all year—they were a big part of the June 14th No Kings rally. For continuity, you can see their old linktree (https://linktr.ee/50501PortlandOregon) which now points to their new one: https://linktr.ee/Nokingsportland
Their discord invite is here: https://discord.gg/cPvCurZq7c
They're active and hold town hall meetings about once a month to discuss upcoming events, mutual aid, and sometimes policy items to pass along to city council.
Rose City Resistance is an unaffiliated group that offers support to every other resistance group in town; think medics, corkers, de-escalators, radios, and the like. They have a Bluesky account that's active here: https://bsky.app/profile/rosecityresistance.bsky.social
Indivisible Oregon were also organizing last Saturday, I'm not too familiar with their chanels, but they do at least have a Bluesky account, https://bsky.app/profile/indivisible-oregon.bsky.social, and a classic email list you can sign up for: https://www.indivisibleor.org/subscribe