From what I know of Nepos he was a generally standard Western Roman Emperor in the sense that it was on fire and nobody short of Aurelian could restore it his dethronement was a case of him appointing Orestes into a position of power and giving his foederati any land. To prevent him from being driven out just don't give Orestes power and keep Ecdicius as magister militum or better yet have Ecdicius arrive on time and kill Orestes. After that debacle, he will still have to deal with the fact he is the Western Roman Emperor and not just a Roman Emperor. Going with the latter scenario the aftermath of the revolt would warn Nepos that his foederati are getting disloyal, a death sentence, he would have to find a way to give them land or reward them to keep them loyal.
The most likely way to keep them loyal would be giving them land the thing they wanted in the first place and what better place than a minor kingdom in the east at this time the Ostrogoths it would probably annoy the Eastern Empire considering most of their military was Gothic at this time but it would be the fastest way to temporarily solve the loyalty crisis although causing some problem in that the future Theodoric the Amal would still be around. After that, he would most likely try to focus on centralizing his holdings in the peninsula and probably try to conquer Africa from the Vandals. Using his alliance with the Visigoths he could use the displaced Ostrogoths and the unsettled foederati to take over the Vandal Kingdom around this time the Vandals and the Eastern Empire were in a truce however this invasion could spur the empire to aid the West but I doubt it.
The success of the war is up for debate but if it does work out for Nepos I would expect that it may keep him from getting usurped and may give him enough prestige to keep his realm together at least for a while. After that, if he is still alive Clovis I will begin to rearrange Gaul including the Visigoths and if Nepos is smart he could probably get some land in Gaul most likely from the Burgundians.
Yeah Idk what else to write the Western Roman Empire was dead at this point and everything I wrote was just delaying the inevitable end when either the Visigoths, Franks, a Germanic tribe, or the Rashidun come knocking and send the Italian peninsula to kingdom come or something like that.