I have had stage II muscle invasive bladder cancer and am now cancer free and doing my own version of maintenance as follows:
You might want to look at taking 95% standardized curcumin wit black pepper extract to both help recovery and possibly inhibit reccurrance, I would reccomend 1000 mg doses posssibly more than once a day. It is know to reduce side effects of treatment.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6277549/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5840955/
Also "timed release" vitamin C is helpful for building the immune system.

There are now less invasive ways to check for reccurance than cystoscopy. You can now take a simple DNA blood test customized for your biopsy cancer DNA. I have taken the Signatera https://www.natera.com/ and just to make sure there was no false negative I also took the Galleri test, which also looks for many other types of cancer. I believe Natura is FDA approved while Galleri is not yet approved, But I think it will be.