Yo this sounds interesting! Can you send me a link once you finish with the program I lowkey want to move away from gimp not bad just slow. As for the crop tool question honestly hard to say.
On one hand the crop tool being a literal crop is interesting, stand out, and give the program that extra bit of flare that makes it unique. On the other hand I feel that it can be kind of bizarre for first time users.
There's also the idea on how the program looks in general when it comes to design everything must flow together and not stand out (Not a concrete rule there are times where having something stand out is good, but yknow what I mean) If all the art tools have these unique icons than the plant would be good, but if everything has more straight normal icons than the standard crop would be good.
Personally I'm leaning towards the plant as it's more fun, stupid (I mean stupid in a nice way), and goofy and I do want more art programs that feel fun and not just all black and white with maybe some gray once in a blue moon.