as far as I know, you can buy OP phone from anywhere and the phone will be genuine as I have not seen duplicates for that brand. I use a 6T and I got it from Daraz when they opened the site some years back for a ridiculously low price

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life Mobile is good. I bought a JBL flip 5 for a very reasonable price and it's genuine.
the OP which is available in SL in from India, and it doesn't matter which country it's from as the build quality is the same. you might have some 4G issues it u buy one from the European market or US..
if I'm you, I won't worry about the warranty that much as all warranty given by local buggers are bull. and the OP phone is very dependable so if you use it with some decent sense it won't give u any trouble.. I have been using OP for the last 10+ years.