Adding a Page Properties webpart to a modern page using PnP Powershell

Hopefully you can use this as a basis for the PowerShell code:

var page = ClientSidePage.Load(context, "Home.aspx");

var components = page.AvailableClientSideComponents();

var pagePropertyWebPartDefinition = components.FirstOrDefault(x => x.ComponentType == 1 && x.Name == "cf91cf5d-ac23-4a7a-9dbc-cd9ea2a4e859"); // Page Properties Webpart Id

var pagePropertiesWebPart = new ClientSideWebPart(pagePropertyWebPartDefinition) { Order = 0 };

List<string> fieldIds = new List<string>() { "20457c05-86aa-4931-9d4b-ea9e5725f40a" , "c5c97a76-74dc-44df-be13-af1b3f660746" }; // You field Guids

pagePropertiesWebPart.PropertiesJson = JsonConvert.SerializeObject(new
{
  title = "My Page Properties",
  selectedFieldIds = fieldIds.ToArray(),
  availableFields = new string[] { }
});

page.AddControl(pagePropertiesWebPart);
page.Save();
page.Publish();

context.ExecuteQuery();