Wikimedia OCR currently uses the free Tesseract OCR engine (which only supports printed text) and the commercial Google and Transkribus OCR engines.
The free [[ https://github.com/mittagessen/kraken/ | kraken OCR engine ]] supports printed and handwritten text. Like Tesseract, kraken is used in the OCR-D project for OCR of historic prints. It is much slower than Tesseract, but sometimes gets better results and would be the only available non-commercial OCR engine for handwritings.
I suggest to start with my free models for German print and [[ https://zenodo.org/record/7933463 | German handwriting ]] (they are not limited to German, but can be used with other languages which use Latin script as well), but there exist many [[ https://zenodo.org/communities/ocr_models/ | more models ]], for example for Arabic or Hebrew script.
I already have implemented a prototype and sent a [[ https://github.com/wikimedia/wikimedia-ocr/pull/89 | draft pull request ]] for Wikimedia OCR.