For example, suppose I enter "πράσσουσα" and it outputs πραάͳοντσα or even, πρααͳ-ο-ντ-σα (root, ablaut, participle marker, feminine). Or I put in πᾶς and it outputs πάαντ-ς (root, 3rdNS), or εἰσώμεθα outputs ἐϝεϳδσαόμεθα or even ἐ-ϝεϳδ-σ-α-ο-μεθα (augment, root, imperfect, past, subjunctive, 1st-person-plural.)? I ask this with the intentions to abuse the language, etymologically spell some words to eliminate ambuguity, reconstruct inflections that shouldn't exist, and enable myself to create new words, and to possibly use in writing fiction. For example, I might try to hastily generate a fake dialect in Greek, specifically marking places that assimilate dental stops not completely dissolving into sigma (τς, δς, θς to ϡ or ϻ, instead of lone ς, to complete the trilogy with ψ and ξ. I would need to know rather quickly whether a word in third-declension nominative singular (& dative plural) that I find with a final-s is made from this assimilation or not.) Another possibility would be a fake dialect that has different rules for contraction and lengthening, so I would need to know quickly and easily where I am encountering an invisible silent yot or waw, and have a better grip on spirious and genuine diphthongs. Can such a device be found, which etymologically and inflectionally dissects words in ancient Greek?
Find? Probably not. There hasn't been much desire for such things.
Make? Presumably. There are systems like Morpheus that can analyze the morphology of a word, and from there it's feasible to break it down into morphemes in whichever way you like. Then you just need to pick a reconstruction you like of Proto-Greek (ideally one used by a solid etymological dictionary), and code in the Proto-Greek form of each morpheme.
Or, alternately, you could come up with a table of Proto-Greek forms of all the affixes you care about, then look up roots in the aforementioned etymological dictionary. This is probably more feasible.
For either of these options, you'll need to deal with the fact that many Greek roots have uncertain origins. Beekes is (in)famous for ascribing all sorts of words to "Pre-Greek", but it's true that there often isn't a solid link back to PIE. So you'll have to decide how far you want to try to extrapolate these back.