I was hearing about this a few hours ago when I was listening to the HA podcast.
It is a nice setup, but could be made so much better with some canvas gauges. In all seriousness, you can use the picture-elements card with a canvas-gauge on top of it. The picture is the extended background of the gauge and can have more useful information; such as in your case (example) if 500 RPM it indicates blank process.
Some examples that I use:
You could to the same for the sensor gauges you are using also, I just have a preference to the canvas gauges. I got the idea from the UV tread here and expanded on it.
https://community.home-assistant.io/t/cool-uv-index-gauge-for-my-swimming-pool-area/116223
@Ali_Kiaie gets the credit (blame) for my canvas gauge background obsession.
It is interesting to see the different cases that people use HA for.