@Gary_Arbuthnot Create a sheet with your 150 artists. As one of the columns, have the Slack [Channel] ID of each artist in this one time setup.
You can now use this sheet and its values as a Linked Record and a Lookup Record.
So if you had a “requested project/artist” sheet, you could have the Slack ID as a Lookup Record based on the selected (requested) artist. (The selected artist field would have been the Linked Record column)
From there, you can set up a Slack Integration. When it asks you what channel, click on the gear to the right of the dropdown and select “Dynamic”. It’ll then ask you for the value. Select the Slack ID lookup record value. In other words, the channel ID of that user.
Hope this is what you are looking for, or that it gets you down a useful path.