Cheapest option is a converter then use the pump that fits the larger valve on both bike. You can get them on Amazon.
https://www.amazon.co.uk/ADAPTOR-SCHRADER-BICYCLE-CONVERTER-CONNECTOR/dp/B078R9164L/ref=asc_df_B078R9164L/?tag=googshopuk-21&linkCode=df0&hvadid=337715828054&hvpos=&hvnetw=g&hvrand=6791544322970584465&hvpone=&hvptwo=&am...