Do you think that is Maine (The Meta) at the end of the episode or Tex?
Keep in mind that we never saw the Meta die (like a fall from a cliff will kill him after all he's been through prior to that event) and the person at the end has black armour which it Tex's colour.
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If Tex were to come back, I don't think her armor would be changing. That sure looked like the Meta at the end. Considering they replayed the Donut conversation during that part again, it may mean that he was mimicking his voice like earlier in the series, or he was simply eavesdropping. We might not actually be hearing Donut.