Esto is the neuter form of este/esta. Since esto is neuter, it cannot be a demonstrative adjective because there are no neuter nouns in Spanish. It must be the subject or the direct object. (indirect object under linguisticly unusual circumstances) . There is really no other option for the subject in this sentence. If you translate it into English This is obviously the subject of the English sentence.
Very simple sentence to understand but grammatically speaking, is there much difference between saying "Esto me va a ayudar" and "Esto va a me ayudar"?Recently taught about IOP/DOP appearing immediately before the action, it makes sense to me for "me" to be right in front of "ayudar".
Well that is how French works, but not Spanish. In Spanish the rule is simpler. In Spanish you can never break up a verb phrase with anything in the middle. There may or may not be a preposition as PART of a set verb phrase like here, ir+a+infinitive is the set expression for to be going to (verb). Of course since this expression does contain an infinitive you could attach the object to it. Esto va a ayudarme. This is quite common im Spanish, although it probably is used even more by English speakers who aren't quite ready to think about any objects yet But if using more than one object in the same expression, the must remain together in either place. The other two forms that accept attached objects are the affirmative imperative and the present participle. The negative imperative cannot accept one. So it is dígame but No me diga.
I am not surprised. Duo has had enough problems with more common contractions like don't, can't and won't. These more common ones seem to have jumped to a little more appropriate for more formal written English, but Duo does need to define a policy, if it has one, regarding contractions. Report it.