Any specs available on that bike's motor? otherwise we're shooting in the dark..
It looks like a geared motor, maybe 250w nominal.
..you probably can't get parts for that motor if it breaks since it's relabeled & who knows how long the bike company will exist.
How many issues are you willing to tolerate?
Grin's all Axle is a ~1000w continuous rated motor.. a totally different league.. you'd need a larger battery and larger controller to utilize it.
I see basically no relevant specs on the website.. but don't expect something you could upgrade for significantly more power... no specs on the battery listed usually means they put the absolute minimum in.
I'd recommend you DIY a bike instead of use a cheap one as a base. It's actually more expensive to do that because you've paid for two electric drivetrains in the end.