Tesseract is an open source OCR engine that a lot of programs use, OCRmyPDF included. There's a number of programs to do OCR for free using it like gImageReader that works on Windows with a GUI. I don't think gImageReader will embed the text in a layer like OCRmyPDF but it will let you get a text document out at least.
JSWolf seems to think OCR on PDF is useless but he's wrong.
If you have Windows 10/11 it's also not that hard to get OCRmyPDF working under the Windows Subsystem for Linux (WSL).
There's also some websites that will do it like
https://www.sandwichpdf.com/