Totem solo air cartridge

RS may swap the internals for you if you are having the problem with the 2-step.

I believe the uppers for the 2-step and Solo-Air are actually different. The solo air system uses a honed stancion, where the 2-step does not, its air system is contained within a tube. If you wanted to convert to a coil, I would be willing to bet they would send you the parts without hesitation in return for you 2-step guts - I did this for a customer of the shop who has 2-step issues. However, coverting to solo air will require an entire new CSU (crown steerer upper assembly) + the solo air system itself. SRAM may not be so compliant, and will probably ask to remedy the problem before giving away that much.

It is possible. I've got a Totem Solo Air that is in a converted 2Step chassis -same upper/stanchions. Disclaimer: I bought it used and the prior owner converted the fork.

You could order all the parts needed, but that would likely take longer.

Might just be easier in the long run and suck it up a bit tos end the fork to SRAM/RS for whatever service you need, and have them swap the parts over while they have it there. I think they were doing that as warrantee service for people with failed 2Steps anyhow.