But I figured a lot of people did buy USB dongles for their desktop, i. e. "set up the old PC for the kids to do schoolwork in another room nowhere near the router." There should be bags full of them everywhere.
I actually have an 802.11b PCMCIA card sitting around. I bought it in 2003 because my university was rolling out a wireless network, accessible in about 1/6 of its surface area, and I was rocking a used Pentium II Thinkpad. Getting Slackware to handle 802.11 in those days was an amusing thing.
The oldnet makes serial WiFi bridge adapters. Fake dial into an ISP like an old machine would expect to and now you have WiFi access.
https://www.tindie.com/products/theoldnet/rs232-serial-wifi-...
There’s also pimodem http://podsix.org/articles/pimodem/
generally it was built into laptops for 95% of the clients... Your typical Dell business laptop from the year 2000 came with a minipci slot and a 2.4 GHz antenna cable, populating the slot with an 802.11b card was an option.
or something like the original apple airport wireless AP and the wifi 802.11b built into macbooks from the era.
or in an even earlier era you would find like PCMCIA/PC Card type 2 or type 3 interfaces with an 802.11b radio and antenna in them to stick out the side of your laptop.