I have a USB key/stick that I keep just for a backup OS that I leave home (the primary) for my 64-bit systems. I also have a 1 GB key that I carry around with a secondary backup OS, a 4th (or more) copy of my most important documents as well a 2-300 MB free in case I need to unexpectedly grab files (which nowadays with the availability of high-speed internet and ease of use of free cloud service seem unlikely). That secondary backup OS is almost 2 years old and is the most recent one of that distribution (Puppy) ; although it's unlikely that both my systems and the primary backup have a problem, I'm a bit paranoid.

I currently have FossaPup64 9.5 and am looking for something more recent that have a GUI browser, PDF viewer, word-processor & spreadsheet for 64-bit systems that its--maximum--size is 600 MB; and just in case it isn't obvious, it also have to support both LAN & WIFI internet.

Thank you for your feedback

Fatdog64 - https://distro.ibiblio.org/fatdog/web/

fat dog appears to be RH7 based binary re-distro, configured

there are more than one choice for thin client / small linux, certainly