It would be nice to add to the firmware the option to use a higher resolution in the fluent stream, maybe 1280 x something.

To be used in the sub stream: rtsp://admin:pass@ip:554/h264Preview_01_sub

You are right. It's so great when we can change the resolution of the fluent stream in your Reolink camera. I often follow this link to configure stream/quality settings. You can try it.
https://support.reolink.com/hc/en-us/articles/360003493394-How-uno online-to-Configure-Stream-Quality-Settings-for-Reolink-Cameras/