Thanks for the welcome! I noticed my old 'core.gz' file, maybe from 16.0beta1 (

) that had 'onboot.lst' instead of "$TARGETLIST" on that line so the bug might have been introduced recently
BTW I've actually been a TinyCore user since v6.4.1. Ran my file server and kids' team websites on an eeePC 701 entirely on a 128MB CF card for years (internal SSD was toast), and also have a Pi Model A running v13.0 supplying the guide data to my DVR since about 2020.
It's still my portable O/S of choice - always in my pocket on a USB flash drive.