I’m sorry you are dealing with that, but they can live a very long healthy life even with ckd!

Just an FYI, the vet kidney disease diets are low protein, which is bad for obligate carnivores like cats. They do it because low phosphorus and low protein works well for humans and dogs, its just not really appropriate for cats. Cats use protein for synthesis of things we use plant sources for, so they just sort of degrade, and you end up needing to do a lot of interventions.

Instead, if you find foods that are made to be low phosphorus but not prescription, you can give a better variety and when they inevitably get turned off to one food, you can swap, or better yet feed a variety so if one stops being available its not a problem.

My cat was diagnosed with kidney disease in 2016 and the vet said even with treatment I’d only get 6-12 mths. He didn't like the vet food so I did a ton of digging into it, and discovered common wisdom is wrong, they need protein but not phosphorus, and over the next several months of trial and error, found some low-phosphorus foods he liked (he liked weruva slide and serve and the core line, especially the tiny tasters, and they are very proud of making foods that are ok for kidneys because if is good for ckd cats, is good for all cats). I added 1/16 tsp coconut oil every meal to boost the calories, as well as occasionally giving him butter or bacon fat as a snack. I also gave him just about anything he would eat, figuring any calories were good calories (he was down to 4 lbs at his lowest, 10 at his heaviest) and he loved chicken nuggets with the breading removed.

Sadly he passed a couple years ago, about 8 years after he was given 6-12 mths. He was healthy (very relative term), active, playful, and friendly right up until he wasn't anymore, and then it was time.