I don’t know that I’d agree with the no contrast on CT/MRI.
Yes, you will have one kidney. It will be doing the work of two.
IMO, you should get fairly regular blood tests (annually perhaps to start) to monitor kidney function. As long as your kidney functions properly, if you need CT or MRI they should be able to be done with and without contrast. This is a discussion for you and your PCP.
If (not saying it will happen) you end up with chronic kidney disease then definitely no contrast for imaging studies will most likely be in order. IMO, you need to know this to ensure anyone treating you does that properly.
FWIW, I have had one kidney for close to 60 years (one was removed surgically almost 60 years ago).
I do see a nephrologist regularly as my one kidney, after 60 years of doing the work of two is loosing a bit of its punch . One needs to be, IMO, an active participant in one’s own healthcare.
Was there anything I didn’t do or take special precautions for, no. I did think about possible repercussions if a horse were to step on my remaining kidney but that didn’t keep me off horses.
If you do donate (and bless you for your generosity), work with your PCP for ongoing healthcare recommendations. We are all different.