Node Provider Matrix channel
There is an open Matrix channel that is intended to be a forum for potential and existing Node Providers as well as anybody else who would like to follow the node provider discussion: https://app.element.io/#/room/#ic-node-providers:matrix.org
The channel runs on the open Matrix network. Matrix has many clients you can use. One of the clients is element.io, which is very similar to Slack, and offers a web UI, a desktop app, and a mobile app.