>Maybe EU wanted to have Russia as a reliable petrostate as an alternative to the USA so they can do their thing without USA?

The decision to rely on Russia was made when USA was a net energy importer, with some dependence on natural gas from Canada, and terrible dependence on oil from whoever could offer any.

To add to that, nuclear was phased out to a large degree because it gets in the way of renewables, as it's impossible to regulate. Nuclear reactor is pretty much an on/off thing and can't safely operate on power levels much under 100% continuously, and if it's off, it can only be restarted in a day, or even a few days. It makes balancing the grid including a lot of intermittent renewables, a huge headache. Renewables already provide more electricity in EU than nuclear ever did, and they cost a lot less to build, and almost all of them were built in less time than it takes to build a single nuclear reactor.

Speaking of the future, all of this discussion is meaningless again, because of time. If we start today, electricity will be 100% solved by renewables everywhere in EU before any new nuclear can be commissioned.