There are tons of 0.3-ml syringes, mainly for insulin…. A single search of “0.3 ml syringe” gave me a full page of options…

https://www.allegromedical.com/products/0-3-ml-insulin-syringe-30g-x-1-2-ultra-fine-needle/

https://www.amazon.com/Exel-0-3mL-Insulin-Syringe-26018/dp/B082J5M3NY

https://mms.mckesson.com/catalog?p=47237+5632193&node=133320+5669365

https://www.adwdiabetes.com/product/21515/monoject-safety-syringe-29g-8881511144?utm_source=google&utm_medium=cpc&utm_campaign=shopping&gclid=EAIaIQobChMIoOLdzo6Q-wIVQ8vICh0fQgpJEAQYASABEgLILPD_BwE