Here is an Amazon link for 0.25mm nozzles. I've never used these nozzles so I can't speak to their quality

https://www.amazon.com/Aopin-1-75mm-Extruders-Nozzles-Printer/dp/B093Q849VM/ref=mp_s_a_1_58?crid=1ALWQGXL4BWU3&keywords=fdm+nozzle+0.25&qid=1683598446&sprefix=fdm+nozzle+0.25%2Caps%2C181&sr=8-58