Chalo is about right. I don't see anything that indicates it is a closed-system OEM ebike (like Stromer, etc).
I couldn't find info on the individual parts, but a google search on the "brand name"
https://www.google.com/search?q=trillium+ebike
finds the seller pretty quick
http://www.ontarioebikes.ca
and a search on their site name finds some subpages
https://www.google.com/search?q=http%3A%2F%2Fwww.ontarioebikes.ca%2F
some of which don't exist anymore, so you'd have to use the Wayback Machine to see if they're archived anywhere, like this
https://web.archive.org/web/2019*/http://ontarioebikes.ca/about.html
https://web.archive.org/web/20190829012259/http://ontarioebikes.ca/about.html
Unfortunately they have a retardedly-designed webpage, which has no links to any of it's subpages, so to visit the pages that have any info about anything at all of theirs, you must use the google search links to get to them.

Great way to run a business is to hide everything from your potential buyers. :lol: Since they made it that hard to access, I gave up trying to find any info on the bike you have, but if you poke around there I bet they have something.
You can't contact them either, because they're "closed for the season", which apparently means they don't give a crap about making any money or helping customers (potential or existing) until they're good and danged ready.
The archived version of their "about" page (which doesnt' even exist on their actual site anymore!) has this contact info, if you want to try them out:
COMPARISON SHOPPING
Ian and Jo Ann Fraser
For more info please Email Us
sales@ontarioebikes.ca
Ontario E Bikes
2149 Quin Mo Lac Rd.
Tweed , ON.
K0K - 3J0
613-920-1847
BTW, this is what their page has to say about their bikes:
Trillium E-Bikes™ are designed in Canada , by Canadians , for Canadians.
We have partnered with well respected overseas manufacturers to bring
you premium quality e-bikes at affordable prices. All our e-bikes
are equipped with quality brand name components that you can trust.
Parts and service are readily available at any bike shop in Canada.
I might be a bit cynical (after having seen so many situations like this), but the first sentence probably means that they came up with a brand name and drew up a logo to go with it that they could have put on a bike, and found a cool looking one (or several) in a catalog of available generic ebikes to put it on. The next sentence usually means that they contracted with a Chinese generic ebike company to ship them containers of a bike in their catalog that looked cool, with that nifty logo they came up with stickered onto it.

The third sentence might be mostly true...the last sentence is not. I seriously doubt that there are any bike shops in any country that carry just the right parts to service any of the e-bike parts of this bike (though many probably do have whatever is needed to service or replace the bike parts of this bike).
That archived about page also says this:
We have spent a lot of time sourcing our e-bikes from well established
manufacturers who supply some of the big name brands in the marketplace.
We buy direct from the manufacturers and sell direct to the customers ,
thus eliminating extra " thumbs in the pie " that add to the cost of
the e-bikes. If you shop around you'll start to recognize some of our
e-bike models , sold by other companies with similar components ,
at much higher prices.
which implies that it's basically about what I said above...even if they *did* spend time finding *good* generic ebikes to slap their logo on.
The "iGo" stuff is likely just another example of that, as are dozens of other "brands". Sometimes that's useful since one brand might not give any specs, another (findable with google image searches, sometimes) might have complete info about at least one part of the same bike, or even slip and give the manufacturer name (sometimes without realizing it is embedded into the part or serial numbers of something, or some other model info, etc., that isn't printed on the bike itself).
Back to the original question.... at a guess, it's a generic 500w DD hubmotor. what would be called a "9C clone" (nine continents, 9cont, etc), wound for a 48v system to give you around 20mph top speed in a 26" wheel. (meaning, even with a non-speed-limited controller, it probably wouldn't do much more than that unless you up the voltage proportionally). A 15A controller means around 750w max power, and that's probably really 15A peak and more like 10A continuous, but you'd ahve to test that with a wattmeter under conditions that would provide that much load to find out.
You can probably use the http://ebikes.ca/tools/simulator.html with the 9C 2807 or 2808 versions to figure out what the motor itself could do for you, given a different battery and controller. First simulate them with the ones youve got (or closest they ahve to them in the list if you don't want to use custom numbers), until you see that it gets you what you really actually get. When you find the motor that does that, then you can simulate with other batteries and controllers to see what gets you what you want out of it, then go buy parts like that to upgrade them, if that's your goal.
It's not a bad deal for a couple hundred bucks, since it works--the main issue you will probably have is that the numbers on things indicate its' probably about four years old, so the battery may have age-related capacity/capability loss in addition to those induced by whatever usage it has had.
Some advice Dogman Dan has given from time to time: always consider used batteries to be worth zero dollars, until proven otherwise...it will make you happier when you find something good, and less sad when it doesn't do what you hoped.