@Marp
1. PLUS BEAT
Plus Beat was one of the first apps we tested, and we were quite impressed by its features. Crafted by XDA Developers forum member Vishal Dubey, this app creates a pulsating effect on the ambient display.

Like most Android apps, you can tweak many features of the app including the pulsating interval. Also, you can select which apps you want the notifications for. You can do away with unimportant notifications. To add to it, you can choose the color of the icons.


You'd need to disable the battery optimization for Plus Beat to do its work. Also, the battery will drain faster if you keep a low interval. An interval of 60 seconds worked well for me. After all, you wouldn't the app to distract you often, right?
What I loved about this app is its Stealth Mode feature. Enabling it will display only the app icons, and not the incoming messages.
2. PIXEL PULSE
Similar to Plus Beat, Pixel Pulse lets you have both the icon and the notification icon on the ambient display. And akin to it, there's a lot of room for customization.


This one allows you to set up quiet hours to stop the notifications for a particular period. Apart from that, you can also specify the start time and the end time for this app.
Some features are paid, and you'd need to unlock the pro version by donating any amount to the developer.
NoLED plays a different game altogether. It doesn't bother you with floating messages or pulsating notifications. Instead, it displays tiny little notification dots. The dots move around to prevent screen burns.

Since the app is a bit old, the default apps are also older. Hence you'd need to add the apps you want to monitor manually. Also, you can cycle between app icons and dots. I found the dot to be the better choice.


It's worth noting that NoLED can display multiple notification dots and the colors can be modified accordingly. Besides that, you can tweak it to show the app icon.

Quite obviously, you have to say goodbye to the ambient display of your OnePlus 6T. Thankfully, this app allows you to display time and day. If that's a deal you are willing to make, NoLED is the best app to have.
4. FLASH NOTIFICATION FOR ALL APP
Flash Notification for All App is the best option if you don't want to mess around with the screen. The interface may look a bit dated, but rest assured that it does its job well. Not only can you pick the flash duration but you can also select the repeat interval. You may want to keep the values a bit on the higher side to save battery juice.


Quite naturally, you can select your default notification apps like WhatsApp, Gmail, and Messages. This app takes a step further and even lets you add the flash notification to calls.

All you need to do is toggle the switch for the unread message count, missed calls, and set the notification apps and you will be sorted.

NOTE: Test the Flash Type before setting it up. Usually, Flash Type #2 works for the OnePlus 6T.