Has anyone seen the article; PICOSMAC - Back to the Past (https://www.nutsvolts.com/magazine/article/picosmac-back-to-the-past?utm_medium=email&_hsenc=p2ANqtz-9-iKf3nzNrQE1qOxpNhmDHkJGvJRboQQEZSzbflaJ3u5nXsC_SC267T3ptwLZoJpVFvnX0RU44lkrvoRDoRHeoihtN5w&_hsmi=387539070&utm_content=387539070&utm_source=hs_email), in Nuts and Volts?
This article is very cool; I like it a lot. I used to have a Cosmac VIP, but either sold it, or gave it away.
Oscar Vermeulen created a handheld emulator (https://obsolescence.wixsite.com/obsolescence/kim-uno-summary-c1uuh) for the Kim-1 6502 computer (https://en.wikipedia.org/wiki/KIM-1 (https://en.wikipedia.org/wiki/KIM-1).) This emulator runs on an Arduino Pro Mini, but you could run the entire emulator with just the Arduino, and use a serial terminal.
Where this fits in to this particular thread, is that Al Williams, from Hack-A-Day, wrote an Elf emulator for the Kim-Uno (https://hackaday.com/2017/07/25/kim-1-to-cosmac-elf-conversion-sort-of/ (https://hackaday.com/2017/07/25/kim-1-to-cosmac-elf-conversion-sort-of/).) Oscar (from the above Obsolescence Guaranteed) says that it should cost around $10 (but that was several years ago) to build his Kim-Uno, and Al has put his Elf firmware up for free on GitHub. That could give you a portable, low-cost Kim 1, and Elf, with just a reprogram of the Kim-Uno.