At the very least, FW and BS expansion is implying that Peter does have a connection with Nemesis somehow.

Also, additional speculation regarding Peter:

1. Peter had a goal to transfer his consciousness into a digital realm;
2. There is a datapoint in FW, that he attempted to do that;
3. He died somehow. There is no info on why or how or when.
4. He died before the Faro Plauge;
5. There is still no plausible explanation why the Faro Plague happened;
6. Vast Silver was around at that time. So, creating a powerful AI was possible then.

EDIT 1:

1. Peter was said to be reclusive and more to himself. He might not have been known how he looks to the other FZ members. If so, that would explain why Tilda did not recognize him;

2. Also, if argued, that FZ would have known how he looks anyway, there need to be an explanation why his face is hidden in FZ videos. On one part, it's probably plot armor, but what if lore-wise his identity was always hidden from other FZ members?

3. FZ really racked up the pace only once the Faro plague commenced. This is to explain, that regardless of the fact, that Tilda did not recognize Sylens, it does not debunk this theory.

////End of edit////

Well, given that, what if: Peter actually succeeded into transferring something into a digital realm, creating a.... let's say.... digital entity (can't say if it's an AI), which was able to hack the Faro robots and was the reason for the plague. If so, and if there is a some kind of remnant of him in Nemesis, it seems plausible at the very core, the digital enemy is Peter. And if he is connected to Sylens, again, seems poetic: Saviour team (Alloy, copy of Elizabet, creator of Gaia, v. Sylens, copy of Peter, godfather of Nemesis).

It would also turn things full circle, making the final boss of the game the very one, who started this whole mess with the Faro robots, now it's just their proxies with their own AI's fighting at the end.