Looking to buy an all-rounder (will be my only bike) for £3000 or less with a 1 x 11 drivetrain.

There don’t look to be too many about in this budget, all I have found is the Canyon Spectral (in either 27.5″ or 29″ form) – is this my only option if I want a complete build with X01 or XX1 or am I being daft and not looking in the right places?

Only other must is full suspension (around 140mm ideally)
Dropper post would be nice, any wheel size will do

I suspect what ever the brand, it will be German. Have a look at Rose and YT bikes, they always come good in the value stakes. Or buy the groupset cheap (again probably from ze Germans) and build a bike around it.

Radon have a carbon 160mm 27.5 bike with XO1 due out soon I think for about £2800

going to be tough! Generally if your going to spec XX/XO then the rest of the components are going to be up specced too, if your ordering from a LBS see if they will do a swap out of the drivetrain for an XX/XO one (some might do especially if the bikes don’t come too prebuilt as they can sell on the parts.)
TBH as much as I would like an XX1/XO1 build for £3k I would be very wary of the rest of the bike at that price.

Buy any £2500 bike, an XX1 groupset and sell whatever it comes with.

On-one were talking about doing the codeine with 1×11, but all been a bit quiet recently

The Canyon Spectral 9.0 EX has XX1 for about £2700. There’s bound to be a YT too. Radon will definitely have something, but their frames tend to be a little more conservative; older geometry and linear suspension.

Codeine29 x01 pike rct3 reverb ccdbair Pacenti on xo1 hubs 2499

Cos drivetrain is obv most important aspect to a bike

I thought it was an elaborate way to get the 1×11 and then sell the rest of the bike, not that you were actually considering the bike based on the gears. That’s almost the opposite of what you should be doing?
Gears can be replaced, shit geometry and linkages can’t?