Hardly anyone is purely Germanic anymore, even Germans have a good amount of Celtic and have for a long time, not to mention Slav and Roman blood thats seeped in from invasions.
Decide which gods are for you, study both lineages heavily. I don't normally believe in eclecticism but I feel that honoring both sides of your ancestry is the best situation if you are mixed, otherwise you will hate one while loving the other.
I identify as Germanic and focus on worship of the Germanic gods but I borrow some aesthetic qualities of Celtic culture including some rites and practices because I am almost half Celtic. I am still unsure about worshiping Celtic gods, I have not studied them well enough yet.