Born in Cork, Scannell is the younger brother of Munster players Niall and Rory and a cousin of Jack O'Sullivan.
[1] Scannell first began playing rugby for Douglas RFC, but switched to Cork Constitution at under-12 level, where his older brothers were already on the books.
He attended Presentation Brothers College, Cork and won a Munster Schools Rugby Senior Cup in 2017, in a side that was captained by his cousin Jack.
[2] Scannell also captained the school's senior side, and started for Ireland under-18s in all three of their tests against Italy, England and Wales.
The deal meant that Scannell would train full-time with the club's senior squad, whilst initially playing matches for the espoirs, or under-23s, side.