UA vs GA4
GA4 is scary at first. The events-based model is at first glance very complicated but it's really not. If you go in with the mindset, that GA4 is easy and a step forward, it is actually very easy.
Universal Analytics (UA) is all about page views. In GA4, you can still see page views but they are just events. It's just a case of creating the report and practically anything useful you reported in UA will be able to be recreated in GA4. I have yet to come across a useful report in UA that I can't recreate in GA4. I emphasise the word useful as there will be some reports that can't be recreated but how useful are those really?
The Google Analytics Help Center is the reference source for the differences. However, for most people, a Youtube Video such as this one is fine.
Rudranil Chakrabortty sells a series of courses on GA4 on Udemy. They are very good and if you are a new user, you can get huge discounts on the regular price. It's worth signing up and buying a set of courses.
Comparing UA and GA4 stats
This is the main thing you want to concentrate on when migrating. You can easily run UA and GA4 together if you use Tag Manager. I would recommend everyone install Tag Manager when migrating or just implementing GA4.
Luckily, someone has already produced a nice data studio dashboard to help you migrate and see the stats side by side.
Thanks to KS Digital
Running the report on this site, I get this
Once you have this dashboard set up, you can see the differences and spot any misconfigurations easily. It's a really handy tool to have when migrating from UA to GA4.
Key Advice
I would just install GA4 via Tag Manager and experiment. The dashboard from KS Digital will show you any differences in the tracking. Unless you are doing something complicated, it should just work out of the box with minimal configuration.
Get in touch if you need any help with migrating from UA to GA4. I run custom training courses tailored to your exact needs. There is no need to learn GA4 if you are just running the same reports as you were doing in UA.