Welcome to the forums!
Probably one of the best ways to get an idea of where you stand is to sign up for Chase's Credit Journey site. (https://creditcards.chase.com/free-credit-score) It provides a VantageScore 3.0 score so you should disregard the score provided, but they also offer prequalified offers once you start meeting their requirements. It could take weeks or months before they start showing offers but once they do, you're usually good to go (but as always in the credit world nothing is 100%).
If you have nothing else chase you might want to start with appying to a co-branded card.
Marriott (100k), Southwest (75k) and United (65k) have monster bonuses out right now.
Forget the CSR in your situation for the moment I would think. CFU would be a nice upgrade though because the Freedom line has better shopping portal bonuses than the Sapphire line. That is one of the best features of the Chase eco-system the shopping portal. AMEX and Citi don't even have their own portal.
Good luck !
Good luck if you decide to apply!
With you being a chase customer, you can either check for any pre approvals via the website on the drop down under credit cards, or just for you, or via chase credit journey. If you have a bank near you, you can always pop in and see if they have any in branch approvals for you that may not be showing online.
You and I are in very similar boats. I am new here, too, the Chase-Eco System is my goal, I have accounts with them but no cards, and I have things unrelated to credit cards suppressing my scores (in my case, it's medical collections, though). From my research here the past couple of months, I reached the conclusions that have already been recommended to you: the Marriot Bonvoy card is the way to go, and I that I needed to be enrolled in Credit Journey.
I'm not going to app until my disputes for the med collections yield some results, but whenever you do pull the trigger, I have seen a lot of evidence - here and elsewhere - that it is worth the effort to call their recon line should you not get an immediate approval.
Good luck to you!