Minimum? Budgets are usually conveyed in Maximum
If your maximum budget is anywhere near ~4.5k, then, as I said earlier, nothing would beat Deco M4 (2-pack).
Connect your current Tenda AC router to the Jio router (via LAN cable - important) and configure it as an Access Point, place it on the other end of house. You'll have to keep on manually connecting and disconnecting depending where are you in the house and signal strength.
Don't bother with Range Extenders, Wireless Repeater Mode, and anything similar - as said by @kage they are neither convenient nor reliable.
Yes, it says WiFi 6 on the official website.
