I wrote a DNS server that did global software load balancing. Essentially it just has a health checking component and a sort and uses that to determine the closest healthy endpoint to return.
Mostly used for cluster failover or in cloud terms it can keep traffic within a zone if possible, otherwise within a region, otherwise closest region.
The reason it was my favorite project is because I was unqualified, but nobody else on my team was a DNS expert. So I got to drink from the firehose and learn. I had a really good testing feedback pipeline where basically visitors to our website did a couple extra background requests on their first page load and we used the web performance timing API to track DNS lookup times and TCP/HTTP times. So I every time I made a change I had millions of performance reports. I could see the impact of my changes in about 60 seconds in grafana.
Between learning something totally new and tying it to a short feedback loop with beautiful graphs I had a great time. Plus that product literally allowed my company to start using the cloud and build multi cloud systems.
Naw. I always think of customer engineer as having a large overlap with the person who quotes you a price for some project (building, car repair, etc).
They look at what you need and try to figure out how to use their companies software to make it happen. But the critical difference is they don't really build anything other than a demo or proof of concept. They might spec out something and give you a cost estimate. Or they might work with you to architect some piece (as in "hey you could use s3 here and dynamodb there and make sure that you don't have a single region point of failure".
At the end of the day it is sales. It's just trying to show people they can use your companies tools to do what they want.
Also I work for one of the cloud companies. I spent most of my career as a software engineer but the most common skill I use is really more devops stuff. Customers aren't asking me to design their business logic, they are often asking me to design their multi region high availability story.