In a scenario where we have added Ederson to our squad?
Strongest pairing Ederson and Fernandes, with the latter as the no.6 and former as the no.8. They could be used the other way about too. Mainoo an option in place of Bruno. Ugarte an option in place of Ederson, but always as the holding midfielder and whichever of Fernandes or Mainoo as the box to box. Ugarte as the no.6 together with Ederson as the no.8, and Bruno and Kobbie together with either at no.6, the less desirable options.
Again, in Fernandes and Mainoo we have one player who is generally regarded as our best and another who is a high quality young player. And for me both have been at their best in the deep midfield pair. So I don't agree with the clamouring for a playmaker to replace them.
There are potentially some great options for a playmaking central midfielder purchase - Reijnders, Palacios, Stiller, Fabian Ruiz or Zaire-Emery, and Jashari spring to mind - but, frankly, i don't believe any of them or anyone we could conceivably buy actually are, or could be, particularly better than Bruno with how he has been performing in a deeper role. And they couldn't play with Fernandes - it would have to be Ugarte (or Casemiro).
Same issue were we to buy more of a playmaking holding player such as Zubimendi - you would want someone more physical to compliment Bruno. Our options for the more gritty, destructive half of our midfield two aren't as strong as the two more technical operators, and Fernandes should be the first midfielder on the team sheet, so if we are to purchase a midfielder they should be more of that ilk.
Are there any no.6s we could get who are great passers and would be an asset in possession who marry that ability with the requisite physicality to compliment Bruno? None come to mind.