From The Shared cM Project 3.0 tool v4 for 439 cM the possibility of such a match being a half first cousin (Half 1C) is far greater than it being a half uncle.
Nevertheless, the latter is also possible:
Relationship probabilities (based on stats from The DNA Geek)
83.17% Great-Great-Aunt / Uncle Half Great-Aunt / Uncle Half 1C 1C1R Half Great-Niece / Nephew Great-Great-Niece / Nephew
15.80% Half GG-Niece / Nephew† Half GG-Aunt / Uncle† 2C Half 1C1R 1C2R
1.03% Great-Grandparent† Great-Grandchild† Half Aunt / Uncle† Half Niece / Nephew† 1C† Great-Aunt / Uncle Great-Niece / Nephew
† this relationship has a positive probability for 439cM in
thednageek's table of probabilities, but falls outside the bounds of
the recorded cM range (99th percentile)