The suggestions above appear suitable for this forum and the best results happen with hard work and draw the shapes of each pixel separately.
This tool works well https://manytools.org/hacker-tools/convert-image-to-ansi-art/go Compared to morgh.us/pixelate/ it gives me the same result as yours and if I tried to reduce the resolution the result of the design is not clear as the logo or image.
This tool gives me the best result and follow the video for editing color and redesign the converted code from your suggested link including the video.
So the combination of this tool and the guide from the video gives me a good result and I can start making a good signature if I start to career this as signature designer maybe the design will be done for a longer time if I don't use some tools like this.
I think you missed my last step man,
And it is a choice, if the designer has the time, creating a signature from scratch is the best way, and it is easier, because most of the time designer make mistake and if we draw from scratch it is easier to track and fix the mistake. But sometimes, we do not have the time, so I use site like morgh.us to fasten the design process.
TBH, the hardest part is not drawing the images, it is finding the whole concept of the signature design because there are already tons of signature, and as a designer we don't want to be accused of something like plagiarism, even though it is accidentally similar to other design.
And by the way, I have tried the manytools.org but it most of the time it do not produce the same image when I copy the code to the forum.