Although I have never understood why it's called rsync, because you need to add --recursive to make it actually sync a file tree, which is what it does best.
xournal for fake form-filling on PDFs - ugly and unintuitive but gets the job done
img2pdf - does what it says on the tin
ranger for managing files and launching stuff - not the coolest kid on the block but this is the single most impressive terminal app I have used in recent years, the key bindings and commands and defaults are so crazily intuitive that I hardly ever even need to consult the manual
Very similar to you. I do use gramma for spellchecking. My most used app overall is probably pandoc. I use it to make all my docs and presentations for work.
For me, it's pretty much just app management via my package manager, some file management, and the big ones are using neovim as a text editor and cmus as my primary music player (I also use emms in emacs sometimes)
I use most of these that you listed, except that I don't use office apps at all, and do all my documents using LaTeX in neovim.
Also, I have small helper scrips for pdf manipulation for tasks that I do regularly, like making my handwritten notes ready for printing at my office since I don't like the algo my office printer uses to convert them to B&W. I also use sejda-console for merging PDFs as it has nice options for manipulating TOC during the merge.
Another nice utility is ffpb which is basically a wrapper around ffmpeg that gives it a nice progress bar.
pdfcrop (commonly included with LaTeX) for cropping margins - it cuts the pdf down to its contents then adds a margin of your choosing, extremely useful for forcing academic papers to have consistent margins, pdfcrop --margins 72 *pdf here* will create a document with a ~1in margin all around (it uses bp as its units)
vips for resizing/converting images - it's a bit faster and lighter than imagemagick in my experience, although the main reason I use it instead of imagemagick is just because I like playing around with stuff I haven't used before :) It has an officially supported python binding too
@antihero I use ffmpeg to extract frames from images. Yt-dlp to download youtube videos. Rmlint, to remove duplicates. Gallery-dl to sometimes download from sites like instagram or twitter & finally mpd / ncmpcpp to listen to music....
convert - convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, etc. Almost nothing it can't do.