I think you'll end up looking at conversion kits, where you have a bike and add the motor+battery system.
The majority of jurisdictions where E-bikes are sold have restrictions on power, speed or throttling that make what you want either illegal or disadvantaged by law. Companies like to be able to sell their bikes in as many markets as possible, so tend to make low power assist only bikes. Because kits are assembled from mixed parts and arent standards checked for import you can get them with more power and higher range packs.
Kits are available from a variety of different companies, mostly online. Ebay works too but quality varies. I suggest joining an E-bike board so you can be pointed toward what is great and steered well away from the dodgy bits that are out there.
The one company that comes to mind immediately for your needs is
FFR They sell kitted out modified trikes but also kits. Also, if you're interested you can see how the motor system developed in this
WISIL page