Sonya,

I have not come across the name Kennellay in Ireland. (There’s no-one of that precise spelling anywhere in Ireland in the 1901 census for example). Names like it are Kenneally which is a variation of Kinneally. You can use this site to see where that name was found in Ireland in the mid 1800s:

https://www.johngrenham.com/findasurname.php?surname=Kinneally

However you suggest the name may also have been Kinley or McKinley and may have Scottish roots. Those 2 names take you to Ulster and to counties Down and Antrim in particular. They were heavily settled by Scots who arrived in the 1600s. What denomination was your ancestor? That may help determine which area of Ireland is more likely. Was he Presbyterian, by any chance? If so, that definitely points to Ulster and to Scottish heritage. (Presbyterianism was brought to Ireland by the Scots, and they mostly settled in the Ulster counties).

Family Tree DNA reportedly has more people with Ulster roots than any other company. That obviously increases the chances of finding a match. If you have already tested your DNA with Ancestry, My Heritage or 23&Me you can upload your DNA results to Family Tree DNA for free and then join the North of Ireland Family History Society DNA Project. Simple instructions on how to do this can be found here: https://www.nifhs.org/dna/uploading-your-dna/