You're correct, good point it wouldn't get FSGS-specific...

You're correct, good point it wouldn't get FSGS-specific approval. If successful and approved it would be much broader, and cover all types of chronic kidney disease including FSGS. So finerenone could legally be promoted/used for FSGS as those patients were included in their trial. Similar situation with the SGLT2 inhibitors that have gotten broad CKD approvals by FDA and Europe and also included FSGS patients in their registration trials. It would be better because then any type of FSGS including secondary type would be covered by a broad CKD approval instead of the DXB situation which excludes the secondary type of FSGS.
In diabetic kidney disease finerenone has given av. reduction in proteinuria of 30-40% vs placebo on top of ARBs in 1000s of patients so it has pretty impressive results already, you can google the published ARTS-DN and FIDELIO DKD trials. I'm not aware of the DMX drug performing to that degree so far.