Glue ear can be so annoying for toddlers balance when walking/ speaking and hearing. They would need to do treatment before assessing him with other delays as it can be related to this.
A lot of those things listed could be due to glue ear! I had to have grommets put in my ears and go to a speech therapist. My speech is completely fine now. If his balance was off he would be late to walk, the hand flapping could just be to help with balance or just for fun. Head shake and items in mouth could be attempts to clear his ears. If he's responding with eye contact and sharing joy. Then try not to worry and enjoy the moments.
A friend of mine’s child had the grommets surgery at 4.75 years, and it was a long agonising wait, after genuinely struggling for a really really long time, so I’d really start banging that drum early, if you think that may be necessary. I really recommend baby sign language. We’ve used a really rudimentary sign language with my daughter from maybe 6m, and it’s really helped. Overall I wouldn’t be concerned about the rest of your list, but I hope you find some peace + support soon x
The speech delay could easily be because of his hearing problems. It sounds like a possibility, I would arrange to get his two year old check (if your in England) done asap, a couple of months early won't make difference. If is in childcare speak to his keyworker and ask them