I'm using Samsung Galaxy M51. This device support NFC but Samsung Pay is not supported. Samsung should provide Samsung Pay option for one touch payment.
It will not possible. M series only get samsung pay mini version may be in future update. but not just useful coz many vendor does not support NFC payment. Full samsung pay required Hardware like MST cheap inside. NFC payment is limited. NFC and MST both required for samsung pay full feature.
M series will never get all features of Samsung pay.. Certain features such as Samsung pay, Dex, wireless charging are meant for their Flagship devices.