we have discussed this same subject over the years and there is still no general agreement.
Kits are tolerated in the EU just as much as here, in the UK. Police over there don't stop e-bikers because they have a kit, but there are anecdotes now and then that some got fined 100 Euros for using the throttle. I have not come across any in recent years but I guess if you pop into a bike shop over there and ask, they'll tell you that the throttle is illegal in the EU and they don't do kits because kits because of their professional insurance and they think that kits are not legal either. I recently popped into a couple of campuses, nearly half of the bikes there are electric and mostly with Bosch motors, so no wonder that a lot of people would happily accept the view that kits and throttle are not legal. All the cheap Chinese e-bikes that supermarkets sell have their LCD locked.
I can certainly ask Kingmeter to supply me with locked LCDs that I cannot change myself or I password protect the settings of the LCDs. I choose not to do so because my customers do not ask me to supply locked LCDs. The fact is that the Chinese controllers are not programmed for a soft cutoff encourages customers to increase the max speed to 17-18mph to avoid the shap cutoff when they reach 15.5mph. They should have been programmed with soft cutoff but they are not. Seach me, I don't have an answer for this. It's not as if it's beyond their capability. Still, I don't want to go down the OSF route because I need the guarantee from my suppliers.