My initial thought would be to go about it the other way, trigger the alarm 15 minutes after the blinds. That would probably be easier.
But that means that you need to redo/rethink and let the blinds be the "alarm" instead.
Otherwise you would have to parse the alarm settings for each day to get the unique (if you jag different times for different days which I am assuming you do) alarm time for that specific day if that even is possible.
I turn on and off my Sonos alarms from within Home assistant but have never thought if it's possible to read the specific time to HA.
The ones I feel I get the most out of are the text to speech reminders that play in the whole house with all of the activities and chores that needs to be done.
Kids laundry days, activities, unpacking clothes, homework etc.
Reads everything from a shared Google Calender.
Automating the kids evening routines is also a good one. Cutting of the network access to TV:s and reminding them it's time to go to bed.
Always there and help them with it but it cuts down on nagging and the argumentation surrounding how long they have watched TV and so on.
Putting on their evening music on a timer, adjusting the volume, lights.
Besides that and the regular lights on/off routines in the whole house the presence simulation when we are away is also a good one.
Having problems with getting object detection working on the Yellow via Google Coral though, rumours say it's doable but no one has actually got it working so I am starting to think it's BS.