We currently do not have plans to add a custom "sleep goal" in Garmin Connect. We apologize for any inconvenience this may cause.
+1 to this problem
I think the point has been missed. It’s not about setting the hours you sleep and getting a tick so you’re proud of getting a green tick. It’s about quality of sleep. You should be able to set the number of hours of REM and Deep sleep as target. That’s what counts.
It is very important to be able to get a tick for the number of hours we sleep. After all, unless we get positive reinforcement from a gadget, our lives are useless. Disregard it’s the quality of sleep that counts, not the length; there’s no target for quality so it can’t be important.