My FR only has one bulb, the reversing light, everything else is LED and should outlive the car.
Yes the replacement of bulbs was said in jest to be fair, however...my worry is exactly what you said... they ‘should’ outlive the car...are they covered under warranty after year 3 if not though...? (Pretty sure I already know the answer to that).
How much is a halogen or even xenon bulb compared to a new headlight unit if they fail...and based on my ‘long life’ led bulbs at home there’s a fair chance at least one will fail after a year rather then the expected 20 years haha. I’ve seen several sub 2 year old cars (admittedly other marques...not SEAT - to date) with head and taillights out on led units.
One of the main reasons I wanted xenon as I can live with £80 for a new bulb (not had to replace one in 8 yrs of owning xenon equipped cars) but not being available on the Leon for 2018/2019 I managed to negotiate in an extra year warranty in the sale so hopefully I’ll be covered for a (probably) £600(ish) new headlight/taillight if one ever fails whilst I own the vehicle.
As for driving in France and carrying a spare set of bulbs...either I only need a single clear bulb for reverse light or I need to get my hand in my pocket for a spare headlight, tail light, etc along with some spanners and an engineering course in
how to remove one haha - at least I can keep them in the useful compartment under the boot floor