Sadly, ancient Greek didn’t have a sound corresponding to ‘f’. Θ was read as ‘t’ with a ‘h’ sound following it (something like how the Irish say “thank you”).
Digamma was never pronounced as the sound ‘f’ according to that link. According to wikipedia, the first time Greek developed the labiodental ‘f’ sound was between the 4th and 15th centuries:
The nicest part is that according to my (admittedly very limited) knowledge of ancient greek, you’d read Οώθ as “Oof”
Sadly, ancient Greek didn’t have a sound corresponding to ‘f’. Θ was read as ‘t’ with a ‘h’ sound following it (something like how the Irish say “thank you”).
This is not 100% correct, they had the Digamma in archaic Greek which was written as F, most often pronounced more like W than F though.
https://en.wikipedia.org/wiki/Digamma
Digamma was never pronounced as the sound ‘f’ according to that link. According to wikipedia, the first time Greek developed the labiodental ‘f’ sound was between the 4th and 15th centuries:
https://en.m.wikipedia.org/wiki/Phi