A Pi4-based rig can feed multiple services; I'm currently feeding six or so, including a semi-provate service that specialises in low-flying military traffic in the UK (I'm just off the main cross-London helicopter route, so get a lot of traffic that wouldn't be tracked any other way than by MLAT from Mode-S).
It was originally set up to cater for folk photographing low flyhing in the Welsh mountains, particularly around the Mach Loop. So it's historically a subscription service with its own ICAO lookup database for military aircraft in the UK, which is very accurate indeed...
Now anyone can subscribe to 360radar, but it is limited to the UK and a small part of northern Europe. It's not the cheapest service, but if you're an aviation photographer in the UK it and its linked community are a key resource.