Today I found out about a variant of the Sd.kfz 251 with 12cm captured russian/copied mortars in a twin configuration, the "Sd.Kfz.251 Ausf.D mit Zwilling 12 cm Granatwerfer 42"
Interesting design and configuration, would be a fun direct upgrade to the existing 8cm mortar carrier.

The next one is the "Leichter Reihenwerfer auf SPW Somua S307(f)", which features 16 French 8cm mortars mounted on captured Somua artillery tractors (Somua MCG).
In practice, this would likely be equivalent to a low-calibre rocket barrage, like a land mattress, and could be used to saturate areas with infantry, or even clear minefields (if explosions can trigger landmines in game).

The final funny is the similarly named "Schwerer Reihenwerfer auf SPW Somua S303(f)", which like the prior entry, is another French artillery tractor(Somua MCL) mounting 20 mortars of 8cm.
Not necessarily unique compared to the S307, but more gun more fun!

Mortar carriers, and mortars in general, feel like a waste of spawn points considering their abysmal accuracy and usually low calibre, but these vehicles add some zest with their unique features. I hope someone else finds this as interesting as I did! ^^

Links for further reading/resources:
https://tanks-encyclopedia.com/sd-kfz-251-ausf-mit-12-cm-mortars/
https://en.wikipedia.org/wiki/Reihenwerfer
https://en.wikipedia.org/wiki/Alfred_Becker (Information available towards the bottom, but details scattered throughout)