Photopea is amazing. Its 90% a clone of PS and is sooo much better than gimp.
I used it today to remove a white background on some of our icons to get a transparent png.
It was as easy as going i to the layer options, blend options, and drag the slider. It even has the option that you can hold alt and split the slider in 2 to get transparency blend as a gradient.
This would be a nightmare in gimp, and photopea does it non destructively. And since its a web app you dont even have to install anything. Amazing.