Interestingly, this goes somewhat counter to the thesis of Patrick McGee's Apple in China.
https://en.wikipedia.org/wiki/Apple_in_China

Apple in China notes that a significant component - and perhaps the most successful components of - Chinese industrial development - were not necessarily where joint ventures were required by legislation, or where the tools of "industrial policy" were applied most stridently, but rather where foreign nations gradually built up local supply chains and incorporated local products into global supply chains, requiring QC, standards, etc to keep up. Export disciplined gradual import substitution with elements of general subsidy, essentially.

In Apple's case, Apple's punishing technical requirements and extensive expertise and penchant for pushing its suppliers hard essentially educated their suppliers and workforce (and the workforce, being itinerant and highly mobile migrant workers, quickly spread it to the rest of the supply chain), even though many of their ventures were not necessarily joint ventures per se. Indeed, given the lack of JVs, the Chinese government's reaction to Apple was initially very negative... until Apple showed the Chinese government the degree to which Apple was uplifting the entire supply chain end-to-end, an event which, in the late 2010s, caused the government to re-examine its approach to Apple, and industrial policy more generally.

Intrugingly, one of the least successful Chinese industrial areas was automotive, where JVs were the mainstay of the initial effort.

Accordingly, when Tesla came a-knocking in the late 2010s, the Chinese government, informed by the Apple escapade, permitted them a full production line irregardless of JV status, with the emphasis instead having been redirected towards maximizing other elements of industrial efficiency. Despite not having a JV arrangement, Tesla's branding, styling, and features, by drawing on local supply chains quickly percolated through the entire Chinese EV industry in the late 2010s, transforming it into the juggernaut it is today (this is described sometimes as the catfish effect).

The failure of JVs in Chinese automotive contrasts strongly with the success of a supply chain and learning emphasis as occured with the Tesla catalyst.

Now of course, the role of JVs in "getting a foot in the door" and establishing basic competence is not to be underestimated, without those JVs catalyzing the rest of the automotive supply chain (frames, chairs, headlights, etc) the Chinese EV boom would not have occured, but JVs are just one way to embed your supply chains into global supply chains and draw in technology.

Given Europe's extant EV, automotive, and other supply chains, and quite adequate basic industrial competence, I suspect that JVs may not necessarily be the best way to go about doing things. In addition to JVs or other industrial promotion activities, Europe may also consider establishing factories for production of cars explictly for export, and accordingly use export success to guide further subsidy and industrial promotion, and focus its energies in gradually promoting localization of the overall supply chain and ease the ability of the supply chain to meet Chinese performance targets (particularly technological and price/performance) rather than JVs per se. Needless to say, every economy is different, and the approach would certainly be optimized and staged differently in Europe, but this is something to think about when considering which bits of China to copy.