disable notification from @here and @everyone on per channel basis

You can mute channels.  You can suppress notifications for a channel for everything *except* @here and @everyone.  The only setting to turn off @here and @everyone is server-wide.

This is a MASSIVE oversight in the capabilities of Discord.  This is something I need to do on multiple servers I'm on.

Alternately, simply make it so that @here and @everyone are suppressed in any channel that is muted and has notifications set to Nothing.