Standing

My baby is 4 months old today and he hates sitting. And tummy time. He has reflux bad so every time we do tummy time during the day he spits up everywhere so I clean him and try again and he’ll just keep doing it . We do tummy time around 2/3 times a day but he still isn’t progressing because he only really get a few minutes total of good tummy time practice. He also hates to sit, he prefers to either stand up or lay on his back, we’re working on sitting up assisted and he just screams after about a minute or two. We’ve tried toys, his favorite YouTube video , the family entertaining him, distraction, he hates it all if he’s sitting. What can I do?