I mean there are three core technologies that make up the steam tank from what I can tell.
1: A steam engine that is light enough and powerful enough to move the armored vehicle while powering the various systems.
2: The steam powered main cannon. Apparently it is smaller/lighter than equivalent Imperial cannons but is shorter ranged.
3. The secondary 'steam gun' which is essentially a steam based 'flame thrower' that sprayed super-heated steam at nearby targets.
Any one of these techs can lead to vast possibilities even on thier own.
The engines divorced from the need to fuel the steam guns means you can create a mobile firing platform or heavily armored ramming machine. Also there are of course civilian applications.
The steam cannon by itself wouldn't need as big an engine to power meaning that you could potentialy get a faster firing and more accurate cannon. No need to measure our powder etc, just ram the cannonball in, get the steam pressure to the needed levels for a shot going X distance and fire.
The steam gun on the other hand would be a little more difficult to manage depending on the amount/heat of steam needed for it to be effective. Though it could serve in a defensive role on fortifications to 'convince' attackers that closing on the walls is a very bad idea.