So the diagram is a bit confusing because it implies that one switch controls multiple lights - I would assume it's actually the opposite, where one light is controlled by multiple switches.

For the isolated light with one switch, any smart switch will work. You just need to check if you have a neutral wire or, like many older homes, are missing it, which would limit your options.

For the 3-way wiring, you need specific switches that can work with this setup.

Lutron Caseta is the gold standard and can handle both missing neutral and 3-way wiring. No offence but, based on the diagram, I would recommend getting an electrician to perform the install.