The problem with Dexcom is the price. A sensor should be replaced every week and costs 80€, the transmitter turns off after three months and costs between 300-400€. If you understand what you're doing, you can easily extend the sensor lifetime to 3-5 weeks and transmitter to 6-8 months.
My take to this is, every T1 deserves a Dexcom system from the insurance. It easily saves your life and makes the control much easier.
Some sensors get noisy sooner than the others. I noticed they work longer during the winter when its cooler. Last one worked for 4 weeks quite good, but in the summer they stopped working in less than two weeks.
I found some pictures of someone replacing the battery on the transmitter of a G6. This is.... not really practical. [1]
What would be interesting is if you could pull out the internals and 3D print a new enclosure that had an actual user serviceable battery.
[1] - https://seemycgm.com/2018/07/12/g6-transmitter-battery-repla...