I work in children's ministry. I just don't expect young children to be still and quiet. Some are, some aren't. It depends on the child's personality and the parenting style.
I would tag team with your husband and any other supportive adults who would take it in turns to take the toddler outside until he's ready to sit still. Don't take him anywhere fun to reward fidgeting, take him somewhere dull and then bring him back in with the books and quiet toys every time he looks like he might sit still. Just keep doing that every time.
Also, maybe counterintuitively, I would sit right up the front where he can actually see and hear what's going on (I say counterintuitive because a lot of parents try to sit near the door to be able to take a crying child out quickly), and then try to engage him with what's happening at the Mass. For example, I would tell dc to look out for the deacon/priest pouring water into the chalice and say 'pour me in, Jesus', or listen out for when the bells ring and pretend to ring along (yes, I have trained a lot of altar servers in my time 😆), or count how many candles there are or what colours are in the stained glass etc. Still have the toys and books too, but he might pay attention to what's going on for a few seconds at a time.
Lastly, if you can afford it, I keep a special set of toys and books just for church, so they stay interesting for longer and are something to look forward to. There's loads of religious stuff available (I had little saints stuffed dolls from Etsy).
Basically, though, I would ride it out by taking him outside all the time until he's old enough to understand the need to sit still. He won't be a fidgety toddler forever!