Welcome to Vodafone Community
I have a Galaxy 7 edge and would like to login and use Facebook and Messenger using my mobile data only and not the internet.
You have a few options
Use the Facebook app.
Use the Facebook lite app I use this as it uses less resources on the phone.
Use your Samsung internet app or Google chrome etc to access your Facebook using the url bar.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.