Since there is no digital wellbeing section in settings on Grapheneos. I want to disable always on display when it's bedtime until morning. How do you achieve this?

Technically yes, you can, but you shouldn't because in order for you to do so you'd have to give an external app, like Tasker, access to dangerous permissions (android.permission.WRITE_SECURE_SETTINGS). Those permissions would give that app access to change tons of settings, not just the always on display setting (DOZE_ALWAYS_ON). Also, you'd have to use ADB, which is extremely discouraged by GrapheneOS staff and many in the community, but if you choose to ignore their advice and you know what you're doing I've already given you all the information you'd need.

I personally missed that feature too when I switched to GrapheneOS, but I don't care anymore because my phone is always charging overnight anyway.

Can Digital Wellbeing be installed and function on GOS?

    f13a-6c3a Can Digital Wellbeing be installed and function on GOS?

    I don't know because I haven't tried it, but if the reason for installing it is to fix OP's problem it'll still need special permission granted to modify "secure settings" since it's not installed as a system app.

      unwat
      I'm still on the factory firmware on P7P and kind of like the new DW, was thinking about installing it on GOS once I switch this weekend, that's why I asked.

        f13a-6c3a
        I was actually curious about this and I couldn't even download Digital Wellbeing using either Google Play or Aurora Store

        Probably not the solution you are looking for but you can put your phone face down and the AOD should turn off.

          DeletedUser80 I am currently doing this, but a native solution is essential. I forget doing this all the time and then realize my battery is drained in the morning. It's a simple enough feature that GOS can integrate it in the AOD settings or even the alarm app.