While I understand that the tech tree is very stiff and why it has to be so that the AI can function properly, I do think that there're ways to improve progression in more interactive ways.
The problem is that there's so much getting packed inside techs (new buildings/units/improvements/policies....) making it feels like the only "tall" progression a civ can have (as in unlock new tools, in comparison to "wide" progressions like increasing city counts/yield/infrastructure/... aka getting more of what you already unlocked).
Thus, we can take care of the issue by splitting tech rewards and put some of them into other appropriate wide progression elements (number of units/buildings/yield per turn/...). This way there're alternative methods to progress unevenly (or rush) without completely stuck on tech tree progression, and it would also AI friendly if we implement them based on what the AI already doing.
A generic example would be, to unlock some specific buildings/units/improvements half a tier ahead based on your current numbers of buildings/yields/units/... you already have at the moment. Already having 10 composite bowmen plus one of the 2 tech leading to machinery allows you to immediately build xbow at twice the hammer price, or 5 libraries and one of the 2 tech leading to education allows you to build more expensive university, effectively skipping maximum of 4 tech (exact numbers can be adjusted for balance purpose). Similarly unlocking based on yield per turn/improvements/trade routes/... or other wide progression elements would also work, and the AI would automatically get the benefits just by going into that general direction anyway.
However, it should be noted that this is ots of work, not so much on the balance side since there're already trade off within the deal, but more on the thematic side where you'd have to specifically pick which conditions unlock what case by case. More of an alternative progression mod idea for more fun/interactive gameplay than actual congress proposal.