It’s January 2026 and I signed up for the premium package hoping words would include a voiced pronunciation sample or at least a pronunciation key. I want to know how words sounded like in Greek, Latin, Old English, … Is this feature in the works or do I have to look elsewhere?
If you’re looking for certainties I’m afraid you’ll better look elsewhere: it won’t take long, there’s plenty of omniscience on the web. Just don’t dig too deep and stop after the first answer, lest you may get confused by too many conflicting Truths 
The sad fact is that, whereas so many written texts have survived almost unscathed for millennia, very few ancient soundtracks have made it to the present days - none at all actually, due to a regrettable lack of appropriate technology: the first documented sound recording dates back to 1857, followed 20 years later by Edison’s phonograph.
Everything about actual pronunciation prior to that is a flurry of educated guesses, some of them plausible, others rather far fetched, a few still quite tempting but sharply at odds with each other.
Just to frame the problem and by no means to debate it seriously, among the plausible ones there’s the sound of the Greek β: if memory serves it was Aristophanes (~400 BC) who reported sheeps bleating “βὴ βὴ”, thus suggesting that the beta sounded actually like “b” and the eta like “aah” - the way we learnt in school rather than the way a modern Greek would utter them (sort of “vee vee”). Provided, of course, that the ovine language didn’t evolve along with the human ones 
Where among the tempting but conflicting ones there’s the archetipal argument about how “Caesar” was pronounced in his heydays: that old glorious (or infamous, you choose) name allegedly gave birth to “Kaiser” and to “Czar”, while the Church of Rome insists pronouncing it “Chesar”.
As such I daresay that it would take a lot of optimism to expect more than flimsy hypotheses and figments of imagination about how the ancient words were properly pronounced. At least until someone invents the time machine.
You should look elsewhere.