Mount is basically that mould of footballer (defensive work rate, ball carrying, goal scoring, passing) that you're describing. For me Mount and Mainoo are interchangable with Mainoo better defensively and Mount better at counter pressing / attacking. FdJ is unique so there's no point comparing.
re: remarks that Unfortunate that Mainoo is injured -- I need the full context. Was that when we had basically no midfielders? Putting together the full narrative is hard because there was a time there was no #8 / DM were available. Mainoo was introduced because there was literally no other option (I guess other than playing McT and Bruno at #6 and #8).
I can put together the list:
WOL: Mount, Bruno, Casemiro (Mainoo injured)
TOT: Mount, Bruno, Casemiro (Mainoo injured)
NFO: Eriksen, Bruno, Casemiro (Mount, Mainoo injured)
ARS: Eriksen, Bruno, Casemiro (Mount, Mainoo injured)
BHA: Eriksen, Bruno, Casemiro (Mount, Mainoo injured)
Bayern: Eriksen, Bruno, Casemiro (Mount, Mainoo injured)
BUR: Hannibal, Bruno, Casemiro (Mount, Mainoo injured)
CPL (cup): Mount, Bruno, Casemiro (Mainoo injured)
CPL: Mount, Bruno, Casemiro (Mainoo injured)
Gala: Mount, Bruno, Casemiro (Mainoo injured)
Mostly Mount has been selected for the #8 role whenever he was available and it's clear to me atleast that this was Plan A for us during the transfer window. Eventuall when Mainoo got in the squad, there was no DM (Amrabat and Casemiro were injured) and McT was the only "#8" available.
EVE we started with Mainoo, McT, Bruno and that continued against Gala, Newcastle, dropped against Chelsea, Bou, Bayern, Liverpool in favor of Amrabat and eventually re-stated. Why was he dropped? He picked experience for a pretty important fixture run through the season.
Sure it's possible he always intended to play him but I don't think any manager worth their salt will rely on a promising young player to start every game. We'll never know because both weren't fit at the same time.