can jio mart gift voucher be redeem in offline shops like smart bazzar ?

AFAIK they are all different franchises operating independently. I dont think you'll be able to redeem it

I asked the local smart bazaar guys why their prices are different from Jiomart and they said they dont have any affiliation with Jiomart. 

But you can use reliance smart gv on jiomart 

I have used jiomart balance in reliance smart point. Ask them to choose jiomart gift card option during billing and need to input ur mobile number. U have an option in jiomart app called pay @ store. It will generate a code and u can share it with cashier

Yes