Baby hates formula

Hello everyone. My son is EBF and i have introduced formula at age of 4 months but baby hates it. Initially he was taking formula and refusing my breast so I had to fight a lot with him and made him leave formula and then thought i would later introduce it, which I did when he was 4 months old including baby cereal and some fruits just to introduce taste. I have tried everything mixing, changing bottles, introducing cup but baby hates formula. I will be starting work soon and won’t be able to pump as I always hated it. I did stop pumping at 6 weeks PP. I was wondering if there is anything like flavour formula milk that I can introduce to my baby for better taste as i know he is very picky with the taste. Any help would be much appreciated. Thanks