The Bible does not give obvious answers, but clues. Genesis 46:34 & 47:3 need to be taken together. First, Joseph tells his brothers to tell Pharaoh they herd cattle, but they actually tell him they are "feeders of a flock" (or, 'shepherds'). Why? Well, Egyptologist David M. Rohl explains that:
"The Anakim pharaonic dynasty was referred to by the native Egyptians
as hekau-khasut ('rulers of the hill country') because they hailed
from the southern hill country of Canaan. Manetho calls them 'Hyksos'
because they were rulers of the shepherds, in other words the
Amalekite nomads of the Negeb and southern uplands. The foreign
dynasty from the far north, which was to appear on the scene a century
later... were lumped together [by Egyptologists] under the collective
designation 'Hyksos' and misleadingly dubbed the whole era 'the Hyksos
Age'. However... the northern 'Greater Hyksos' dynasty was not of the
same descent or ethnicity as the 'Lesser Hyksos' of southern Canaan
who preceded them." [p251 The Lost Testament, Century 2002]
He adds that scarabs of King Apopi have been found, and that he was the penultimate Hyksos ruler.
This might make sense of Joseph's brothers apparently disregarding his instruction to tell Pharaoh that they herded cattle (Genesis 46:34) for 3 verses on, they replied to his query about their occupation, "Thy servants are shepherds, both we and our also our fathers." Or, "we are feeders of flocks" according to the Robert Young Literal Translation.
Before his brothers were presented at court, Joseph, the Vizier of Northern Egypt, told Pharaoh all about his family arriving and that "the men are shepherds, for their trade hath been to feed cattle; and they have brought their flocks and their herds (Genesis 46:31-32). Given that Joseph had already told Pharaoh that they herded both cattle and sheep, the mention in 47:3 of them being shepherds (without adding the bit about cattle) might be there as a clue as to the significance of Pharaoh's title meaning he was king of the shepherds (or, king OVER the shepherds). The brothers were seeking Pharaoh's governance over them - shepherds - recognising him as king over shepherds. That would please Pharaoh.
Joseph ensured his brothers ate at tables separate to the Egyptians in his household, and even Joseph had his own table, separate from both groups. And his house was built in the Syrian style as of his father and forebears, not the Egyptian style. Joseph knew the dangers of mixing with the Egyptians, that they could lose their desire to see God's promise to Abraham fulfilled in them, so right at the start he sought to keep a distinction between his family and the Egyptians. That point is made in Matthew Henry's Commentary [p69] where he adds that Goshen
"lay nearest to Canaan... and well furnished with pastures for
cattle." As to shepherds being "an abomination to the Egyptians"
(Genesis 43:32) Henry explains, "they looked upon them with contempt
and scorned to converse with them".
That is why the land of Goshen is significant as to their settlement. The less contact they had with the Egyptians, the better!
While his brothers were staying in Egypt, Joseph ensured they lived separately to the Egyptians, for the land of Goshen to the north-east of Egypt was not heavily populated. Joseph was careful to keep his brothers as herdsmen AND shepherds, which could be achieved in that corner of Egypt. That is why Joseph did not try to get his brothers into high positions of office in government or trades - not to incur the envy of the Egyptians - but to keep them as distanced as possible and therefore less likely to mingle, for their shepherding would continue.
As for your secondary question, “Is this a deception”, Joseph knew the Egyptians and their worship of pagan gods and goddesses, and wanted to ensure his brothers and family remained pure in their worship of the one God, the God of Abraham. Sheep and rams were sacred to the Egyptian god Amon and cows were sacred to Hathor. The Egyptian bull-god Apis was considered a manifestation of the king, as bulls were symbols of strength and fertility, qualities that are closely linked with kingship. The Egyptians also worshiped the pagan deity Khnum who was represented as a man with a ram’s head. Khnum was one of the earliest-known Egyptian deities, originally the god of the source of the Nile. Since the annual flooding of the Nile brought with it silt and clay, and its water brought life to its surroundings, he was thought to be the creator of the bodies of human children, which he made at a potter's wheel, from clay, and placed in their mothers' wombs. He was later described as having moulded the other deities, and he had the titles "Divine Potter" and "Lord of created things from himself". https://en.wikipedia.org/wiki/Khnum
Here we have the religious reason for the Egyptians treating the Hebrews with contempt – the Hebrews worshipped YHWH as the Creator. They would never worship Khnum or any of the other Egyptian deities. In Exodus 8:26 what is the "abomination of the Egyptians"? This link shows that, no, deception is not involved here. Joseph had extensive knowledge of the Egyptian religious system and habits, and used that knowledge to carefully guide his family into settlement in Egypt, thus fulfilling the prophecy to Abraham about his descendants serving the Egyptian prior to eventually entering into the land promised to Abraham.
Before the Exodus and after the plague of flies, Pharaoh gives permission for the Hebrews to make sacrifices to God, but only within Egypt. Moses said that would not be right: “The sacrifices we offer the Lord our God would be detestable to the Egyptians. And if we offer sacrifices that are detestable in their eyes, will they not stone us? We must take a three-day journey into the desert to offer sacrifices to the Lord our God, as he commands us” (Exodus 8:26).
The fact that the Hebrews would sacrifice and eat sheep or cattle is probably the main reason the Egyptians found them to be detestable. Exodus 12 describes how the Hebrews slaughtered a lamb, roasted it to eat and painted the lintel of their doors with the lamb’s blood. The angel of the Lord passed over them and they were preserved. The first-born of all the Egyptians died. This was a powerful lesson to both the Hebrews and the Egyptians as to the true Creator and the Almighty God. The gods and goddesses of Egypt were shown to be impotent and false. The Hebrews worshiped the Creator, not the created.
