Converting long-scrolling screenshot to PDF on Android without white background

Suppose I have a long-scrolling screenshot that I took with a phone, and when I convert it using those apps, it looks like the screenshot is just put on the regular-size white background page as you can see below. > I know there are lots of Android apps that are able to convert images to PDF, but the problem is all of them, mostly, include a white background. I've tried the online version as well, but still the same. I know this is possible because I used an app called Xodo, it only converts the first image without background, but the page from 2 to the end has a white background around it. Do you know if there's an app that could do that or another way, so it's just the screenshot being the page, with no white background included?