MMDVM doesn't convert from DMR to analog. You would need more software bits to do this. It's definitely possible using DVSwitch.

You would need separate interfaces for DMR and analog though, a CM108 interface (repeater builder USB Rim Lite, RA or DRA would work) AND a MMDVM Hotspot. You might not want to run these all on a Pi. My bridge runs on a Vultr virtual machine though I'm planning to move it to a Dell Micro desktop to save the $5 a month.

Using DVSwitch you would be using Allstarlink to interface to the analog side as a half duplex node, then using Analog Gateway to interface with all-star using chan_usrp, then transcode to/from DMR (you can use the md380 emulator or buy a AMBE hardware device), and then you'd have to interface that back to your pistar MMDVM Host using a brandmeister TG (you can use your DMR ID as a talk group). You could also run your own HBLink locally, but that gets a bit more complicated.

It's a fun way to learn a lot about how Allstarlink and DMR networks actually work.

We're currently using DVSwitch to link the NB1RI network to Brandmeister TG 3105992 which lets me use the K1EWG repeater in my garage to monitor the network. I did this before I added a 220 repeater in my garage that's linked, but now I can monitor it both ways. Oh, and I also linked an IP phone in my living room to the 220 machine running Allstarlink, so plenty of options.