My tuppence worth, using your list.
Martinez - in a normal window would agree, but given the churn and the likelihood his replacement costing more than the income, it might be best to keep him.
Digne - Ditto
Rogers - Hopefully not unless the money is ridiculous. Not trading the above for a net loss should reduce the need to sell.
Buendia - Gone for £15-20m.
Bailey - Gone for £5-10m
Watkins - time to say goodbye and thanks for £20m
Barkley - release to reduce the wages.
Garcia - hopefully break even? Add the fella at Leipzig too.
Onana - I’d sell for £40m ish and buy Luiz.
Add Barranchea, Guessand and Malen leaving for £75m ish
Ultimately that’d generate £100-150m and we’d need to buy Luis (£20m?), first team striker and winger, plus a back-up for Cash. Just about possible with the odd loan and free transfer too.
Good luck Olabe. Interesting (worrying?) that he gained his reputation buying academy players rather than the oven ready players we probably need.