Don't agree - particularly over the period from about 2017 - 2019 when Levy had his hands very full with the stadium problems.
Apart from Levy being a fairly early champion of the DoF system in PL #, in that 2017-19 time period he just didn't have the time he had previously had to deal with transfers, so with Poch implied threat to leave if a Dof were appointed, Poch took over more and more power.
Coaching and buying players requite two totally different skill sets and whilst I've nothing but admiration for Poch coaching (except sometimes timing of subs etc), I saw no evidencde that he was good at selecting players to buy, putting together a development strategy for youth players (probably including loans) etc.
BTW, I absolutely do think that Sissoko was Poch's choice - certainly would not have been Levy's choice to spend £30m (then equalling our highest transfer fee) on a 27 year old where there would never be any resale value. Levy would probably have found a cheaper midfield player or suggested buying 3 good younger players such as Maddison, Grealish and Brooks for the same money.
My guess is that Poch saw Sissoko's strenth and powerful running as key to replacing Dembele and thought he could coach Sissoko into that role.