Save command line output to a file without any graphics or special characters
You’ve got several options with that tool.


Output JSON and parse that
Upload to Google Sheets and export as CSV the text you need
Use a tool to strip the ANSI escape codes that prettify (in the opinion of some) and color the text - one package to strip ANSI is https://github.com/chalk/strip-ansi
Use other tools to strip these out by piping the output or saving it to a file - https://unix.stackexchange.com/questions/4527/program-that-passes-stdin-to-stdout-with-color-codes-stripped or https://superuser.com/questions/380772/removing-ansi-color-codes-from-text-stream
Trying to set your terminal type to TERM=dumb (like Can&#39;t plot with gnuplot on my Mac) 
forking that project and changing the code so the ANSI escape values are nothing. (Lines 4-8 here https://github.com/paulirish/pwmetrics/blob/master/lib/utils/messages.ts or perhaps a few lines down where those variables are used to construct the output)


I would also tell the program to write your output file so you get a clearer view without needing to debug file handling and pipes in bash (assuming that’s not your strength here today).