You can create sidebar sections (https://slack.com/help/articles/360043207674-Organize-your-sidebar-with-custom-sections https://slack.com/help/articles/3600432

You can create sidebar sections (https://slack.com/help/articles/360043207674-Organize-your-sidebar-with-custom-sections https://slack.com/help/articles/360043207674-Organize-your-s...) and put all the un-important channels in there for manual review. Deactivate notifications for most channels and only keep them on for the super-important ones. Just ignore the less important ones that are hidden in the sections. If you get pinged with urgent things all day long that actually do demand your individual attention, then that's a workflow/cultural issue that Slack settings can't help with... maybe block out DND/focus time on your calendar?