Mistral isn't even close to the most used AI services in the EU, there are very few industries where EU sourced/hosted models are required (mostly ones where the US also either mandates US models or is seeking to...) and the potential behaviour of the
US government (rational and irrational) is at least as big a contributor to European companies being cautious about dependency on US cloud models as EU regulation. Regulatory hurdles exist to building datacentres in the US and basically everywhere else, and don't favour Mistral over any other company, and European states and the EU are busy funding [notional] competitors
It is not, even really stretching the definition, a state sanctioned monopoly.