It's possible to find .32 and .36 barrels for a Hawken or Renegade but they will be custom. And heavy. A .54 Renegade barrel is lighter than a .50, 1-inch flats but less metal as more is bored out, and so on. I have seen some .32s for both models pop up for sale on various sites/forums, even as recent as this week. You need to dig and watch daily. For what you see priced just for a barrel, for a little more you might be better off buying an intact rifle, if you have the time and patience to wait and watch.
Seneca and Cherokee barrels are the same width dimension at 13/16, but are not the same length. I have a Cherokee in .32 and would defer to someone who owns both to say if they can be swapped and what the issues may be. I think the foremost issue would be with the under rib on the Seneca being too long to fit a Cherokee stock... not sure, maybe it's the other way around.
I had a complete spreadsheet of all TC models and dimensions and their inter-changeability and now I can't find it. With a little more digging you can put together your own based on confirmed information from various forums. If I ever find my chart, I'll post it.
From memory and other notes I do have, FACTORY original calibers and measurements across the flats...
Hawkin .45 and .50 are 15/16
Hawkin .54 is 1-inch - I do not believe this will work in a Renegade as the barrel wedge and under rib will not match the Renegade stock.
Renegade .50 and .54 are 1-inch
PA Hunter and White Mountain .50 and I think WM had a .54 are 15/16 and stock/barrel compatible; Hawkin barrels might fit these but I do not believe these will fit the Hawken stock.
Big Bore .58 is 1-inch and should fit a Renegade stock
Cherokee .32 and .45 are 13/16
Seneca .36 and .45 are 13/16
Two barrel sources, Rice was posted above, you can poke around and at least price shop as a starting point. Others here know far more than me about other custom options:
https://ricebarrels.com/https://thegunworks.com/product-cat...parts/barrels/oregon-barrel-co-drop-in-rifle/