My mom needs a new phone. She is used to Samsung so Samsung it is. A54 is 400€ and S23 is about 800€. Is S23 that much better?
Samsung don’t have screen protectors like in OnePlus from factory. So installing them without dustor air bubbles is gonna be tough.
A54 would be more than enough. Bigger screen and battery will be more valuable for mom. I have S23 and my gf A54 and we are both happy with our devices.
For screen protector I would recommend tempered glass from Spigen, it has frame for easy alignment and I never had any air bubbles with it.