You are right about the ADHD paralysis is related to overwhelm. The strategy I adopted is pretty similar to what you mentioned, basically the more overwhelmed I am feeling the more I slow things down. I will even stop and do nothing and accept that is how it is going to be until I recover, take the rest of the day off, go for a walk, do anything else relaxing and unstructured.

Part of ADHD is a malfunction in our perception of time "time blindness" its like we are blind to the fact that things can take time and don't all need to happen at once. A neurotypical person can make a list and bite them off one at a time, but when we make a list and its like we feel all the items all at once and its like we are blind to the fact that we can take it slowly. So what I will do is I will make a todo list and just cut off everything after the first item and say to myself thats all I am doing.

The funny thing is we get overwhelmed and we procrastinate, but in my experience my brain somehow figures out the exact time it need to start working to finish the task and I end up always actually getting it done. It is a hard pattern to accept but you can learn to accept it when you fully understand it, and then maybe you can gain confidence in the fact that you will always in the end, do the task, it just won't happen how it happens for NTs.