You can still say hi, with the first message of the day, that's a nice human touch, and not the point here: say hi + what you need to say, that's the point

Good morning can be nice for that but if you actually have something to say make it the first part of the same message as the content.

Saying Hello or good morning and then spending multiple minutes composing your actual message while I'm attending you is extremely annoying.

Quite frankly though I don't think it makes sense to do any of that outside a group chat. Just say what you want to say and get out.

I just send it as one message. So something along the lines of:

Hi [Name],

[Message content]