In 2025 France exported 31TWh to Germany and Belgium and imported 4TWh. I would say the issue with nuclear is that it cannot follow load changes quickly and therefore needs other sources to compensate peaks. There has been a time a few years ago with maintenance issues you are right. However right now it is available at 85% which is a high score. In comparison today, a cloudy day, only 14-20% of solar and wind renewables are producing power.

Availability values here: https://analysesetdonnees.rte-france.com/en/generation/generation-availability

I’m afraid it is rather the opposite. Sometimes Germany exports electricity to France, but most of the time it is the contrary.

“ France has been an exporter on all its borders: a very strong exporter on the borders with Germany and Belgium, Switzerland, Italy and Great Britain”

https://analysesetdonnees.rte-france.com/bilan-electrique-2024/echanges#Detailparfrontiere