I’ve never had an issues putting a ‘normal’ unlimited phone SIM into a router – we have a static caravan, it’s the only way we can get data into it. We ended up with the 4g version of this one and it’s been working fine for over a year.
Zyxel 4G LTE-A Indoor WiFi Router | Share Dual-Band WiFi to 64 devices | Supports VoIP/VoLTE | Unlocked
The office that my better half rents has really poor wifi so I got her one of these a couple of months ago:
TP-Link Cat6 Gigabit 4G Router with Sim Slot Unlocked, 1200Mbps TP Link 4G Router with sim slot Unlocked, 4G Mobile Router with Nano Sim 5Ghz Dual Band, MU-MIMO technology
Both from Mr Bezos, alternatives are available.
Also just been fine and works. They’re both 4g rather than 5g. In my experience it all hinges on phone signal where you are – we started with Vodafone at the caravan after testing it with my work phone, ended up with loads of buffering. Swapped onto Spusu (piggiebacks on EE) and it was much better, much stronger signal where we are. As mentioned above streaming telly eats loadsa data so you might be surprised how much you can use, unlimited data plans are the best way.