I use a locally hosted YaCy instance with cached results to work around this scenario. Much of the content I am interested in is kept locally, so it’s good enough. When I have a bunch of “read later” tabs that pile up, I copy all their URLs into the crawler form with “Store to Web Cache” checked and it accomplishes what I described. Just another option to consider.
The dive utility helps tremendously for exploring the filesystem contents of a container image. Combine that with the output of `docker inspect` to look at the metadata and you should be able to have a good understanding of what it will do when running as a container.
You could also use the vim :%!python3 your_script.py (where your_script.py does the work to format the text) command that takes the text of the buffer as stdin to the script and replaces the buffer contents with stdout of the script. This can also be combined with visual mode linewise to only replace specific lines of the buffer (must work on entire lines selected).