Personally.
I would give them my number on the understanding it is not to be passed on to others without my consent, and simply use my own phone.
I have loads of call and data spare on my deal and would rather use my own nice-ish phone rather than fart around with carrying two phones and charging them up swopping sims etc.
Some here are moaning about companies not meeting them halfway etc, but won’t walk an inch to help out a company themselves.
“Cutting off my own nose” and going to lots of hassle to prevent what looks to me like a tiny irritation is not for me.
I buy my own nice-ish work clothes, boots, and gloves rather than use any cheapo stuff offered.
(I even buy my own Biro pens without claiming back the money!
But keep that a secret from those who will only accuse me of subsidising the capitalists!)