Being "failure free" when PWD wants to do hard things

I understand the idea of failure free activities and that there are books on it. My question is:

If the PWD insists on doing something that is bound to fail (let's say trying to scratch off stains off a dirty napkin or a couch cushion), all I can try is to distract with something else. But PWD wants to be left alone to do it, and since the stains can't be scratched off, PWD could get frustrated that the stain won't come off.

If a PWD tries to use something difficult (let's say using a remote control), but simple to assist with, I try to intervene and help. I can help to change the volume or channel, and take away the device. But that doesn't work all the time, if the dirty napkin is already in hand. Pulling it away seems to cause conflict. Any suggestions?

I tried to do something like go grab a clean napkin and try to swap it, hoping it would satisfy a need for a clean napkin, for example. That can sometimes work. But at other times, the cleaning of the napkin can turn into a compulsive activity. I can attempt to see if there's a deeper need, such as getting something clean, and maybe I can provide a dry-erase board to clean.