Last 4-5 months and it's very difficult to establish a dummy. It needs to be estsblished much earlier to provide the comfort long term. So you have missed the boat with the dummy- I'd get rid since it's serving no purpose by the sounds of it.
OK, this morning's posts put your OP in context.
It does not work. He just gets more and more distressed. Falls asleep as soon as you pick him up but then can take a while to get into cot / crib in the middle of the night.
I’m wary of making generalisations but shouldn’t he be able to self soothe a bit now?
He is not going to be anywhere near being able to self sooth. Because you've never taught it.
To teach him to sleep independently (ie in the cot, not on you) he is going to cry. A lot. A dummy stops this because it's physically impossible to cry while simultaneously sucking. But you don't have a dummy established - So there will be crying. A lot. A very lot
So your initial decision needs to be deciding where your priorities lie with regards to no distress verses quicker independant sleep.
The quicker you want independant sleep, the more distressing and crying there will be.
The slowest, gentlest methods towards independant sleep will have time scales in years.
The fastest, harsh as methods to get independant sleep will have time scales in days.
Then there are all the spaces in between- all of which will involve some degree of crying. Basically because your baby is using the cry to communicate to you that he is tired and wants to sleep and needs help to go to sleep.
So how quickly are you (realistically) hoping to have baby sleeping in the cot?