As many others have already pointed out: it's currently not the best time to buy hardware. FWIW, you could have grabbed Star Labs' StarLite^[Which, quite literally, happens to be a "tablet with a keyboard".] last year for 750 €. Currently, it starts at 1014 €.
Btw, OP, perhaps I'm obnoxious/oblivious/obtuse (or what have you), but I wasn't able to parse what you mean exactly with Linux compatible hardware. If it's not too much trouble for you, could you be very explicit?
EDIT: At one time, the StarLite was available for 416 (!) £. At least, as per this article of GamingOnLinux.
Then, please, could you help me understand whether a device with the specs found below does (or does not) satisfy you:
HP EliteBook x360 1030 G2
If you don't want refurbished, then how about the following device?
HP Chromebook x360
And, finally, if you actually want somewhat modern hardware, how about this one?
Lenovo Chromebook Plus 2-in-1 14