Milan has one of the biggest trophy haul but they failed to capitalize on their success and develop the brand. Coupled with the Serie A decline (average TV rights), Milan is nothing but a name nowadays. Of course, they had their influence in FFP being relaxed for new owners (just after City and PSG were punished for the same thing haha) but they are now in the muds with FFP slowing their comeback. Inter played smarter and even them had a tough time under FFP. They could only do some loans with option to buy (that they wouldn't use) under their FFP agreement. And this is with Suning giving them a good help and selling their academy players for a fortune.
I don't usually take PL clubs as an example to show off the good outcome of FFP due to the anomaly of their TV rights. When the bottom clubs are winning more money from their TV rights than the champions of every other leagues bar Real/Barça and maybe Bayern, you cannot use it as a model. The model is what is happening in the other leagues with one big club monopilising the league : Bayern 8 in a row, Juventus 8 (soon 9) in a row, PSG would have been the same story if the now defunct Monaco didn't manage to get one before getting killed by FFP.
However, let's talk about Spurs. While they did almost everything right, everything perfect, what did they achieve exactly ? No PL title, they got into the UCL finals like a Monaco (1 year fluke), got ousted by RB Leipzig just after the groups the following year, no domestic cup title and now they are in a really bad position to hope to get into the UCL spots. The biggest success of Tottenham while overachieving is building their stadium and it would have been possible outside of FFP.
I guess Juventus Turin would be the most accurate club to define success under FFP. No PL money, they were in Serie B a decade ago, they built a dynasty in Italy, they did 2 CL finals, they did some power moves with Cristiano Ronaldo and de Ligt, they built a stadium.
Atletico Madrid too. Winning a league against the duopoly and being a regular in the late stages of CL.
Tuchel doesn't have a big fanbase among PSG fans. Not only did he manage to lose the domestic cups but PSG didn't really improve in CL, PSG had a serie of defeats at the end of last season with a record of conceded goals (meaning the coach cannot motivate its players anymore). And his ideas of recruitment are all terrible. Terrible ! You should always do the contrary of what Tuchel is asking if you want to be right (or at least not wrong). As it stands, Tuchel has not done anything beneficial for PSG. We rely on Neymar and Mbappé doing some magic. Other than that, it is poor, very poor. The only good thing i see about him is the fact he is giving youth quite a lot of playing time. And even then, it is useless since those bastards aren't even repaying his trust by signing contracts with us.
Edit : you wanted to know about the development of players. Neymar has developed as a complete playmaker but i wouldn't say it is due to Tuchel but because of the fact he is allowed to go into the middle of the field ala Messi. He was always an elite footballer. Mbappé has developed physically and he takes more responsaibilities in the attacking play but it is due to him growing as a man and having more experience. He is still lacking in areas like the long range shoot, the headers, his back to the goal play. His recruits like Kehrer or Diallo are either injured or not reliable enough. Kimpembé had an horrendous post World Cup year and is still unreliable. And the youth players are not sticking long enough with us to say more. His only success is making Marquinhos hold the midfield due to the fact the other options were/are miserable.
Tuchel won't be missed.