Just to clarify — in fact, there is no separate “Offline POS app”. Offline functionality is an integrated part of POS module, which itself is a part of ERPNext, which itself is an application, built on Frappe framework. The latter is platform independent, but requires modern browser.
One big guestion by my part, the POS offline works yes, but i dont have connection to internet or to the server on the moment i open the POS i cant do nothing, its only offline after i connect to it!
if you are offline in the first place you can not connect to POS
you need to initially load the module - for that you need connection to your network if selfhosted or internet if cloud hosted
“Offline” in this case does not mean without any Internet/LAN
it means the POS once opened does not necesarily require server connection to make or end transactions
I could be wrong but mainly this just speeds up the Process of making a POS transaction as you dont need to wait for the server to answer all the time