I'm a big fan of fd and use it as a part of my dev workflow as it's way easier than find.
I've used it to convert files on the fly for ingest, specifically converting xlsx to csv en mass.
This is the command I was running:
$ fd . -e xlsx -x sh -c "in2csv '{}' > '{.}'.csv"
This finds all the files that end with xlsx (using -e) and executes (-x) a shell command that passes the full filename {} to in2csv (part of the csvkit tools) and outputs to the basename {.} with .csv appended.
Except I found that this wouldn't work in certain situations. At first I thought it was because I had spaces in my filenames, but then remembered: [fd] ignores patterns from your .gitignore, by default.
Since xlsx files aren't required in my git repo they're ignored. So this TIL is more to make sure I don't forget, to ignore the ignore file -I is required.
$ fd . -I -e xlsx -x sh -c "in2csv '{}' > '{.}'.csv"
Simples.