@Noruletz
As long as it has an HDMI input, any streaming device will make it smart again.
The big 4 are Roku, Firestick, Chromecast and Apple TV+.
Most come in an HD version, or a more expensive UHD version. This is usable on an HD or HD Ready TV though, and is the more futureproof option if you think you will be upgrading to that. Though a new TV may have the apps native, so food for thought.
Apple TV+ is the best, but costs £150, about three to six times the cost of the others. Perhaps not worth it just to boost an old TV. No HD version, only UHD, but as above, usable on lower resolution TVS. Comes as a small box, connects to TV via an HDMI cable, is mains powered.
Chromecast doesn’t have the Channel Four app. As we regularly watch Countdown on catchup, that rules it out for us. But YMMV. Comes in an HD version £35 and a more expensive UHD version £60, again usable down to HD Ready., Comes as a dongle you plug directly into an HDMI port, runs off a USB cable for power, mains adaptor supplied. Chromecasts used to need to be started from a phone or other device, and still can be, but the modern ones can work standalone, like sticks do.
Firestick comes in a range from simple and HD £35, to powerful and UHD £70. I find the Ui cluttered and confusing, but some people prefer it. All sticks that plug into an HDMI port, USB powered, mains adaptor supplied.
Roku comes as the Express, a little unit which connects via an HDMI cable and a supplied USB/mains adaptor, in HD £30 and UHD £40 versions, and a Stick, UHD version only, £50, likewise supplied USB/mains adaptor.
The UI is a clean grid of apps, the device is cheaper model for model than the Firesticks, and is my favourite. I have 5 TVs kept smart with the above devices; 1 Apple, 1 Firestick HD, 2 Roku Expresses UHD and 1 Roku Stick.
All of these are standalone devices, and your only expenditure would be the purchase price. Any apps you use, like Netflix, Disney+, etc., will require an extra subscription to the app provider just like they would if you ran them direct on your TV, but there is nothing to pay the device supplier beyond that purchase price,
But look up Roku and Firestick on the web, and see if you come to the same conclusion or not.
My favourite bedtime reading is a Sony product manual…
