The bikes sold as "gravel bikes" will have more relaxed geometry. Easy enough to change out the wheels if you decide you want different tires. For touring you will want a bike that has a removable battery so you can have a backup in the poop van and so you know you will always have a fresh battery to start the day and it makes it easier to bring just the battery inside for charging each night. The removable battery aspect elimiates many bikes with middrive.
To me a Class 3 bike is going to be the most natural to pedal and not have the motor cutting out when going up short grades. The Giant E+ bikes do not have removable batteries but they have the Yamaha drive unit and also the Giant e-bikes have longer chain stays and a more stable geometry.
The bikes made for triathalon use have the best geometry for touring and the Scott Centurion was the first bike that worked as well as the custom built frame I had made in 1974 to my specifications. Gravel bikes are second best and they are available as e-bikes.
When I first started long tours in California there were so few bike shops that I had to carry spare parts and tools. It is much the same today with regard to finding someone to fix anything on an e-bike on a tour where you will be days away from a shop that can work on the bike. I would put the removable battery and the most bike available shops for support for the bike at the top of my list. In the USA that means Trek or Specialized at this point in time.
The fender mounting and adding water bottle holders is easy with any frame so no need for there to already be bosses in place. The requirement of having a belt drive motor also seems silly as these also break and if I was worried about a chain failing I would put on a new chain prior to a tour and keep the old chain in my luggage.