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There are no baptismal records available for Co. Donegal back to 1818. Co. Donegal is one of the nine counties in the North which are part of Ulster Province.
McLaughlin is a very common surname in Co. Donegal. I checked the Tithe listings as you did and there were over 500 McLughlin records in a number of parishes in Co. Donegal.
I would look at your top DNA matches particularly any with a McLaughlin in their tree and contact them and see if you can make a connection.
You can also add Hugh's emigration story to our XO Chronicles site https://irelandxo.com/ireland-xo/history-and-genealogy/ancestor-database