Dual boot problem-I can't see both drives

I've had a lot of trouble lately getting even the latest versions of some of my required software to run on Sonoma, so I retro-graded one of my 2 boot drives to Ventura. Took a while, but the process went fine. The M1 Mini came with a half-terabyte internal drive (Boot512) and I installed a 2TB external drive (Crucial2TB). Boot 512 now runs Sonoma 14.1.1, and Crucial2TB runs Ventura 13.6.1. One problem remains: a glance at the desktop doesn't tell me which disk is in charge. The topmost disk is always the external drive, whether I boot into Ventura or Sonoma. The Sonoma disk, Boot512, never appears. In order to search it, if I need to, I have to click on the Ventura disk and bring up the Favorites/Locations/Tags directory. Is there any way to make the Internal drive routinely visible on the desktop, like TM and the other Volumes?