Microsoft Dynamics 365
We need to enable the PO and Purchase Request from Point of sale
on 11/7/2022 2:59:08 AM
A feature is delivered in 2022 release Wave 2 to support the creation, editing and confirmation of purchase orders in the POS Inbound inventory operation. - Boyce Zhu, Principal Product Manager, Dynamics 365 Commerce
For now you can receive POs created from D365 in POS.
Usually by business restrictions, stores cannot create POs by themselves - this is D365 process, because you need to select the best matching vendor, control prices and etc. - too much responsibility to give this to stores.
Also as POS is usually used to serve customers, for PO creation makes sense to use D365 Mobile app or PowerApp.