It's customer service/support and parts availablity that you need to check on. All these ebikes are not being supported very well once a problem arises. Ensure you can get tires and tubes locally, or be prepared to wait awhile for them.
A guy came into a bike shop while I was there just to get a flat repaired. The shop used the excuse that they did not have the correct inner tube (never even pulled of the tire to attempt tube repair!) and sent him away. Places are not working on ebikes unless they sell that particular brand. Check for authorized service shops for a specific brand before buying.
People are getting stuck with bikes they cannot get serviced except maybe at a dealer (they are mostly sellers, not service shops). The problem then becomes you need to buy a more expensive (often 2x regular cost) bike from a major brand just to have a reliable source for parts and service in different areas if travelling.
Ask what a replacement battery costs first and see if they even have any available before you buy. Also, recommend you get a spare battery upon purchasing because what is available now might not be in a year or two, and they certainly won't any cheaper to buy. Ask for a deal on a spare battery (10-25% off) as a condition to buy the bike. This applies to any brand. As a prior sales and service shop owner I can tell you I'd rather lose a little profit on a part than to lose all profit on a sale. Actual cost is not a guanrantee of a better bike; often times it's just features and accessories you are paying for and not quality.
For as many people I see enjoying their ebike I see just as many suffering the issues already mentioned; and on essentially new/barely used bikes. They are breaking down. There is a major rush to produce these vile (just my opinion) things without proper quality control at the manufacturing level and proper assembly at the distribution/dealer level.
For some reason I see and hear about tires/tubes regularly failing with little mileage. I ride tiny 23-25mm tires at 100-140 psi and I just finished cranking over 1000 miles without issues on a 40 year old bike; I am not hearing ebike owners getting that type of performance; and if they do it won't be happening even 10 years down the road. I am not saying they are all bad, but the industry is not that sound even after a decade or more of existence. There is a dedicated ebike forum out there; I recommend you post your question there as well.
Ask how long a company/brand has been in existence. Ask how long a specific model has been in production. Do not be led astray by low cost. Also, if the dealer does repairs; look around and see if they habeca bunch waiting to be serviced or that have already been serviced. Call customer servicecand find out where they are based at; if not local to your country I would pass.
Sorry to be the voice of caution and reason, but the reality of thie industry's downsides is not something I wish to invest in at this point it time. Maybe in another 5 to 10 years, but by then batteries are going to be outrageously expensive. Remember the e-auto industry, as well as other industries are consuming lithium at a high rate; and they are all expanding at an exponential rate just like the ebike industry. Lithium, the new "fossil fuel" will disappear at an alarming rate and recycling it will become the next major industry. Everyone should get some money for old batteries just like lead batteries which have nearly doubled in price over the past 20 years even though the market rate for lead has been fairly level during that time.
Good luck! You'll need it.
I own several Velotric ebikes and I'm been very happy with them. One of them is the Fold 1 Plus. It has a legal 750 watt motor, 75Nm of torque, cruise control, 20-inch wheels, OTA firmware updates, rear turn signals, Class 1, 2, or 3, torque sensor AND cadence sensor, and a 2-year warranty. I think they are currently on sale for Black Friday.