In other life (or so it seems now), I spent a few years preparing wills for a living. So I've uploaded a draft document to here for you, Caran:
http://dl.free.fr/bxz7NjG2i
(As with my crosswords, simply click on the grey box to download it. You can then open in Word or any similar program. There's absolutely nothing 'private' about it; if others here want to download it, and perhaps to comment on it as well, they're more than welcome to do so).
Even though your brother hasn't previously written a will, I've left in the standard provision that revokes previous wills in my draft text. It's simply put there to prevent his executors having to search for any (non-existent) earlier wills in order to see if any of their provisions are still valid.
His executors can be any adults at all but it would make sense for them to be younger than your brother (so that they're still alive when he passes). There's nothing to prevent your daughter from being an executor and it might be simplest if she was. (If she's married, her husband could perhaps be the other executor).
Your brother needs to sign the will in the presence of two witnesses, who can be any two adults EXCEPT your daughter. (My latest will was witnessed by a couple of friends in a pub garden. The previous one was witnessed by a couple of people, who I happened to be working with that day, in a Tesco car park!).
While it's currently possible for wills to be witnessed remotely (e.g. over Zoom), I'd regard it a preferable for it to be done in the traditional way. (e.g. by your brother signing the will in his back garden, with the couple next door witnessing him doing so).
Once your brother has written his will (and had it witnessed), he needs to think about where it will be kept. (It will be of no use at all if nobody can find it!). The simplest solution might be for your daughter to hold it for him.
If you've got any questions, just ask!