Would you agree or do you think Chelsea and PSG would have been all the same with Guardiola coaching them (all else equal)?
No they wouldn't be the same with their present form. Having money is another thing and how to spend and manage your money is another thing differently.
Gaurdiola is an expereience coach that knows what he needs,we have seen how he has converted Man city into a great club and the strongest presently because he has the skill and knowledge of doing that. PSG is a rich club also with Chelsea but the lack the quality of a good coach. Buying the right players at the right time is what matters alot. Chelsea will be doing better and might have even won EPL if it was Gaurdiola that was their coach,same with PSG. Behind every successful club there must be a great coach and not money. Though.money can turn things around but that is when there is a good manager to make it happen.
I think Chelsea or PSG would had been better with a coach like Pep Guardiola because he's a kind of coach that could transform any team into one of the best within a short period of time if given the right backings, he's proved it over the years and even with his current team Manchester City who are currently the strongest team in EPL and current Champions League holders, there are some coaches you'll backup with funds and support but they'll end up recruiting the wrong players that doesn't suit their system but Pep knows how to recruit players that suits his style and pattern of football and transform them into quality stars, he's highly experienced in building a team that could challenge any other top clubs across Europe and that's what makes him very outstanding.
Both Chelsea and PSG are clubs with rich owner and are financially stable of giving Pep the right backings he needs imagine if it was Pep that coached PSG when they had, Messi, Neymar, Mbappé, Sergio Ramos and other top class players in their team, surely they would had won the champions league or even played in the finals.