Okay, so I've decided to buy a smart TV. The cheapest option would be to buy a decent HD LED TV and a firestick or any other streaming device.
Now, first of all does 4K make a huge difference? If so then I'll have to buy a 4K smart TV (since there are no non-smart 4K TVs and a 4K Firestick (for app support) But this cost is same as buying a pure android 4K TV (such as Sony Bravia) which renders a streaming device unnecessary.
What do I do, please help me.
There are non smart 4k TVs just typically small and lower quality.
I would argue 4K doesn't make a huge difference but the HDR/Dolby Vision does and it is neat impossible to find a TV with 1080p and HDR/Dolby Vision. There are some super small ones out there though and you would be better off with going with a 1080p pc monitor with HDR (BenQ EW2780 as example).
It ultimately depends on what size you want and what features you want. For the most part I would argue ignore the built in smart TV because it will be obsolete in a couple of years anyways.