Hi @E_G,
Solution provided by @v-yuazh-msft is taking 10 latest unread messages that are in "Inbox" folder. No validation against time when they arrived. If you need so, there is needed to add one more condition to validate it. So finall Flow will looks like this:

The formula in condition looks like this:
@greaterOrEquals(items('Apply_to_each')?['DateTimeReceived'],addhours(utcNow(),-8))In this case the time is utcnow() that means 5;30 - 8hours that means 21:30 to make it simplier.
When there is met this condition then I'm setting help variable "isTrue" to true, variable is boolean. And after this loop I'm checking this variable and if it is true then I'm sending notification, if not nothing happen.

Hope this is helpful.
P.