Any double din unit should go in physically without much trouble as they're a standard size. The tricky bit is the wiring. At the very least you need an ISO wiring loom/adaptor, but you don't want to lose the steering wheel buttons operating your new radio so you really need another adaptor for that too. This complete package worked well for me:
https://www.dynamicsounds.co.uk/toyota-alphard-2002-2008-double-din-car-stereo-fascia-stalk-fitting-kit-black.html
It has everything you need. Fitting my head unit was a doddle apart from the backup camera wiring which was a massive pain, but that's another story!
You said don't need sat nav, so you might consider an even cheaper unit (£47!) that will mirror the sat nav on your phone:
https://www.amazon.co.uk/Camecho-Bluetooth-Android-Support-Steering/dp/B07P5CWX65
Not that I bought one myself - mostly because I'm not convinced the steering wheel controls will work it (but I may be wrong). I also really wanted CarPlay and DAB so I bought the cheapest option with both, namely a Sony XAV-AX1005DB (£260). Not cheap but it "just works". I also get a really solid DAB signal after fitting a £25 DAB windscreen antenna, so maybe the same will work for FM, dunno...