The A34 is a good device that can be customised with many settings for everyone. However, it does require a certain amount of starting knowledge. Once everything is set for the right person, it is easy to operate. It is important that the settings relating to battery consumption are optimised. Otherwise the mobile phone will have to be charged every day.
A cable with USB-C plugs on both sides is supplied for charging. This requires a mains plug with USB-C.

Well, it's just as complicated/simple to use as any current Android phone. In other words: You can set it up accordingly with widgets and quick selection buttons on the home screen to make it easier.

In principle, any commercially available power adapter is suitable for charging. If you want the maximum charging speed, it should have 25W or more. As the included cable is USB C to USB C, the power adapter should also have a USB C connection.
For my part, I use the part here for this:
Samsung Power Travel Adapter (15 W, Power Delivery)

You can use any power supply unit with 25 watts, regardless of the brand. I would make sure that the charger has USB A and USB C. If you want to use it as a senior mobile phone, there are quite good apps in the Google Playstore, just enter senior mobile.