Thanks to Rob Inman for sharing this link over on Discord. This was supposed to have been posted in July 2019, but I just found it in my drafts folder. I think I was going to write an article about it, but forgot.
Someone in the UK is selling an all-in-one RS-232 to WiFi adapter. They use Bo Zimmerman’s excellent Zimodem firmware, though the version they use is based on my fork of the project with the defaults set to standard RS-232 rather than Commodore’s inverted RS-232.