To screencap a long manhwa, you could try using third-party screenshot apps if the default methods don't work well for you. Just make sure to download them from a trusted source. Another option is to scroll through the manhwa section by section and take multiple screenshots to capture the entire length.
One way is to split the long manhwa into sections and take multiple screenshots. Then stitch them together using image editing software. It might take a bit of time but works well.
You can download manhwa apps that offer offline reading options. Some popular ones include Webtoon and Tappytoon. Just make sure to check their settings for the offline feature.
In many cases, it is legal to read manhwa online if it's from authorized and legitimate platforms. But reading from unauthorized or pirated sources is illegal.
Another must-read manhwa in 2020 was 'The God of High School'. It combined exciting battles with a compelling narrative. The diverse characters and their growth throughout the story made it a standout.