I have difficulty remembering appointments, so rely heavily on Nextcloud calendar to remind me of appointments across devices. Despite spending early reminder notifications, I still miss important events.
I am in the habit of checking my email early in the morning. It would be beneficial to receive a daily schedule via email in the morning, so I could plan my day better.
There is a daily agenda email feature in Google Calendar and Microsoft Outlook, but I would really prefer to use Nextcloud 
You haven’t written on which device you’re missing the agenda view. For the web gui an issue ticket already exists which covers this function. It seems that someone is planning to work on the implementation soon.
For Android devices you can use the build in agenda view in the calendar app.
For iOS devices I cannot tell you how the implementation status is.
I check my email from various devices. It would be really helpful to have a daily agenda sent to my email first thing in the morning 
Afaik, sending an agenda by email isn’t planned yet, This is usually not necessary because the calendar apps on a mobile device can be used to display the information. For the web view you have to wait until the function has been implemented.
I like this idea.
My wife doesn’t need to be bothered throughout the day by reminders from my calendars, nor I from her calendars. But it’s often helpful for her to know what I have going on during the day. Also, I don’t have appointments every day. I do not have to look at my calendar every day. So, I almost never look at my calendar, despite it being a widget on my phone home screen. I do read my e-mail every day. Having a reminder in the mailbox on mornings that do have events could be helpful for avoiding surprises.
If a cron process ran overnight / early AM and queried the day’s entries from a particular calendar and did minimal formatting for plain text e-mail body, it could send the daily agenda to my wife or me or a boss or secretary.
Without looking at the database, it seems this would be a fairly straightforward query of calendar x for event start (today) or event stop (today), then send email to specified recipient process. The hard part seems like it would be the web interface to configure which calendars should be treated this way and to whom the agenda should be sent. But then, I hate building user interfaces and rarely program anymore … To a web guy, that might be the easy part. it is basically a two field table the way I picture it.
Why inventing the wheel twice? As I already wrote, you can save time by using the build in agenda view on your Android device. You can switch the view within in Calendar app or use the available widget to show the requested information on a finger tip. See e.g.:
As I said, there is already a non-google agenda widget on the home screen. It doesn’t work for me because I don’t have appointments every day so that part of the screen has been learned to be unimportant. My brain just blurs it as I go for whatever I opened the phone to do. That screen real-estate would be better utilized for quick access to tools I do use every day.
For me, e-mail is important and read every morning. What works for you may not work for others. YMMV.
I am glad the existing setup works for you. It’s not terribly useful for me. Can you see that different people do things differently from how you do them? Can you permit others to have differing opinions on how things should be done?
Maybe you are the author of the relevant code and therefore only your opinion matters on this topic? I don’t know. If you are, I’ve put in my 2 cents and will shut up. If enough other people chime in wanting the same thing, maybe the author will implement it. Maybe not. I’m not making any demands. I have no right to make demands of people writing software that I don’t pay for directly. All I have done is voice an opinion. Everyone has one. They all stink…
I’m not the developer nor do I want to tell you that there is only one solution for a problem, but I’m a friend of “keep it simple” solutions. Someone has to develop a solution which requires maintenance in the future and this is very often the problem afterwards.
You wrote that you’re already using a non-google agenda solution. Does it rely on the calendar database or dies it use a custom database? It might be worse to test a different widget/app.
The non-google agenda widget works well. It stays synced to my Nextcloud via DAVx^5. The part that doesn’t work is my brain’s patience for checking things that do not change often.
A daily email with the agenda of the day will be a very helpful feature. This solution might integrate other apps of the next cloud too, but firstly for events and maybe dated todo’s would be great.
this look kind of nice to have