If you need more than the one decimal place accuracy of looking in Effect > Amplify, there is now a plug-in for that script. See https://forum.audacityteam.org/t/peak-amplitude-analyze-plug-in/31723/1 .
There is no way to store or reload scripts across sessions using Nyquist Prompt. Do you want to vote for that?
Perhaps Nyquist Workbench (not yet released) can do that? Steve would know.
Gale