So, I just googled if sleeping nude is common in France and while it is not really common there is a highere than twenty percent in some questionnaires where people stated that they do this.
The thing with Q is that even if he were not attracted to Picard like he is he would not really mind all that much since he voiced his opinion on how unnecessary he thinks clothes are when he was in the turbolift with Worf.
Q would just snap his fingers and get naked as well.
Headcanon! That Picard is used to sleep naked in his bed all his life, cuz he ain't shy of his body and hey, it's no one's business;however since Q’s constant appearance in his chambers ans particularly in his bed, he had to change his habit on something more covered but still air-ventilated
One time the Enterprise comes across a new cilization/a space ship from an unknown species but they already know a few things about Starfleet and especially.
And when Picard introduces himself, the unknown aliens are like 'Oh yes you are Qs husband. We have heard of you'
And everyone on the Bridge stays at a shocked Picard as if to collectively ask him if there was something he .. forgot to tell the rest of them.
I couldn't tag you for some reason and so I chose to answer your comment about Qs guilt and how that would cause him to be overprotective towards Picard after the Borg Trauma this way: How Q felt about Locotus and his own involvement is generally a very interesting topic and it could be really inteeresting if at one point things just started to work out mysteriously well for Picard but with Q having experienced most things about human existence as something 'bad' this could quickly escalate.
I must say I think this makes perfect sense for everyone involved. Like Q knows being human sucks in a deep level. But he risks smothering Picard so it's pretty much a judgement position.
Even though I still consider ST:Picard as more of an AU than canon, I do think that TNG!Picard meeting Picard!Q would be interesting. Because Picard!Q is ancient and mature but also kind of mad in a way that TNG!Q isn't. And I think for Picard it would be like meeting an old, wise but slightly unwell king while he still has to deal with his much younger 'spoiled prince' version.