I have the Toshiba Fire TVs and they work great without any external streaming device. In my opinion, the smart tvs have greatly improved in the last 10 years. My old "smart tv" could never connect to my streaming services well and so I always used a roku to access them.
Both my current tvs were bought in 2020 and I no longer need a roku device to access anything.
With the Fire TV, you can easily add pretty much any app out there via an Amazon subscription or through an outside subscription. I have prime and netflix plus free services like tubi, freebees, etc. And I pick and choose paid apps (hbo+, britbox, amc+, etc) on a temporary basis - pay for a couple months to binge watch shows, then cancel when I'm caught up. Note, I do not have cable or satellite, so all my subscriptions are a la carte.