Something like this?

https://www.thomann.de/gb/harley_benton_traveler_steel.htm

Even that isn't, strictly speaking, small enough to qualify for most overhead locker rules – all of the so-called 'travel guitars' are generally at least 20cm or so too long for most airlines' rules, but I think you'd get away with it. I don't imagine most airline staff would quibble over it.