The only one of the signatores in the EU at the time was the UK. The Ukraine was not allied with any EU country at all. "We" certainly never gave our word to protect them. That the US and the UK were not willing to honour their guarantees is their responsibility.
German car makers have problems because the future for cars (esp. fossil fueled cars) looks bleak. And Corona hurt car sales in the present. Otherweise their position is good. It is hard to find car makers in a better position.
As for China, market share of German cars is still rising.
Chancellor Merkel’s coalition has refused to provide incentives for the purchase of conventional cars, leaving carmakers disappointed. Car sales have taken a battering due to COVID-19, but there is a silver lining.
www.dw.com
Germany’s car manufacturers are once again being bailed out by China. Having skidded to a halt in February, Chinese vehicle sales are rebounding—particularly at the luxury end of the market.
www.wsj.com
A lot of worker regulations is EU-based so Polish workers do get the same benefit as French in a lot of ways. And more than the workers in the Ukraine and Belarus - or in the US. Maybe next year they get more protection than those in the UK as well. All thanks to being in the EU.