Monzo have publicly said in the past that they don’t intend to issue chequebooks as they consider cheques obsolete, or at least on the way to obsolescence.
This is why they also haven’t joined the cheque imaging clearing scheme (ICS) to process cheque deposits - they get cheques processed on their behalf by a third party, to avoid the need for being a member.
Starling, as a member of the scheme, process their own cheques but still don’t issue a chequebook.
As others have said, no neobank currently offers a cheque book at all. The “closest” are the challenger banks, which would perhaps include Virgin Money and Metro, but they are more similar to traditional high street banks than they are to neobanks like Monzo.