The iptv will run fine till a EPL or ECL football match is on, then all channels could go black.
Router is a) more expensive b) more complicated to set up
Firestick a) easy to setup b) has dedicated vpn apps c) means you're not tied to the limited iptv apps available on your smart tv d) cheap as chips
Sometimes because people have a tv that can run iptv, they think they must use it for iptv. Don't make life more difficult for yourself by thinking like that.