Analytics with a large number of landing and advertising campaigns?

Question

Google Analytics

Started working for a service company. Prior to that, he worked in an online store. Everything was simple there - 1 IM, 1 counter, 1 CRM. There was a convenient end-to-end analytics.
And here are a bunch of landing pages (landing pages), each with its own counter and each with its own set goals. The top funnel (from traffic to lead) is analyzed in counters (Google, Yandex). The lower (from the application to the lead) manual excels, after analyzing sales in CRM
If the analysis with the lower part of the funnel is quite simple (there are utm tags coming to CRM), then in the upper part there is complete chaos due to the number of landings and counters.
Please tell me:
1. How to do end-to-end analytics if there are a lot of landing pages (pages for different channels, cities, services). Do not put 1 counter everywhere ....
2. How to automate the funnel calculation process and, most importantly, where to conduct it? Transfer via special systems, take the fact of a sale from CRM to Google Analytics or vice versa from analytics and build a report in Excel ....
I want to understand at any time in which part of the funnel the conversion sags and through which channel. And also to understand which landing page works better and whether we fit into the limitation of the cost of the sale.
KPI for us is CPO if anything...

Answer 1

GA API pull any data to where it is convenient for calculation