Yes, the ZX81 can do it, too.
The ZX81's audio capabilities are seriously limited, meaning it simply lacks any sound chip or DAC or anything, thus everyhing. But it does write and read data to audio cassette tape recorders, sooo...
...precisely. The MIC and EAR connectors on the ZX81 are in no way meant to deliver what a sane person would call sound, but of course it still is an audio signal, only in a very crude way. ZX81's BASIC only provides the LOAD and SAVE commands to access the tape ports, so some machine code is required to get in control. The idea is not really new, but it looks as if "Sound Digitizer" by NICKMANN Studio is an exceptionally nice implementation. Also the accompanying article (see link below) gives a lot of interesting and helpful information about the fundamentals of digitized sound.
Here you can see and hear it in action on NICKMANN Studio's YouTube channel (2023-03-16):
Check out NICKMANN Studio's website for more information, and don't forget to send some coffee:
https://www.buymeacoffee.com/nickmannstudio/zx81-sound-digitizer-english
