A solid and settled defence will help any keeper. A decent defensive midfield presence will protect that defence and allow it to keep its shape which in turn will help out the keeper.
If Allen and Doucoure had been available consistently and we didn't have an obvious right back problem, I suspect that our goalkeeping worries would not be so high.
Having said all that, a confident and able keeper allows the defence to become settled and gives them confidence to allow the midfield in front of them to do their work and it's a virtuous circle of each player working for the other.
I think that there will be no keeper being bought in the near future unless circumstances fall in our favour such as a decent keeper becoming suddenly available or someone pops up with a decent bid for one of Pickford or Olsen. In the meantime, Pickford and Olsen will be adequate if not satisfactory goalkeeping options. I think sorting out Olsen's feet and Pickford's head are the priorities for now (though for their age, this should have been done long ago).