Giving my kidney cat fluids used to be a nightmare - she couldn't be less interested in eating anything, even the treats she does like, so those tactics weren't effective. Then, trial-and-error led to this game changer.
Get your hands on some sliced biltong (similar to jerky in the US), soak it in hot water for a few minutes, then run it under warm water while you press and rub it until the spices and salt have sufficiently diminished. Test it yourself. While administering the fluids, rub the washed, stretched out meat over your cat's mouth and nose throughout. It practically deactivates them! Like touching a shark's snoot.
When you're done, give them whatever treat they do enjoy to close with pay-off for the kitty-appealing smell/taste. This part is important for keeping them interested in the biltong.
It's best if they get pet-intended treats, but if they're only interested in the biltong, ensure you've rinsed the salt and spices off thoroughly. Cutting off the edges helps in that regard.
For anyone struggling, I hope this helps.