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First launch was 2011. Even my GPS watch can use it.
https://the5krunner.com/2018/06/26/garmin-935-and-galileo-935-gets-galileo/
Of course, my watch (and all Sat Navs) will still work if access was removed as they can still use the US GPS system and/or the Russian GLONASS system (assuming they were designed to talk to them already).
I don't think there's a single commercial system that is Galileo only.
Sat Navs will stop working on a hard Brexit if they use Galileo? Good to see that the MoS is still spouting unadulterated bullshit.