Keep perservering with it and giving it when they are calm and happy or sleepy/sleeping is better than trying when they are upset as they're much less likely to accept something unfamiliar then.
Both my BF babies had/have dummies and it never interfered with BF. Bottles are far more risky for that. DD1 had one from day 5, she was super sucky! Accepted first one straight away. DD2 had one from 3wo. She took more time to accept it and get used to it, they are all so different.
I know many mums who got their baby o accept a dummy/bottle first time in their sleep. It seems a good way of getting them used to it
Good luck and keep us posted!