Where you can find the actual UF2 files for PicoMite/WebMite is buried under a link from PicoMite Firmware Version 6.02.00a for use on ClockWorkPi PicoCalc, specifically Index of /download (HTTP not HTTPS), where you can in turn find the relevant UF2 files (I can’t take you further, as for some reason I cannot access the site from my work right now, even though I could access it from home earlier).