I recently purchased and tested the Apexel 100mm Ultra Macro Lens for coin photography with my Google Pixel 6 cell phone camera.
The lens looks like this:

I took a picture of a 1904
Indian Head cent with the phone camera without the macro lens:

I took another photo with exactly the same setup with the macro lens:

In both cases, photos were taken with the Android Open Camera app. I used manual zoom and positioned the phone / camera as close to the coin as possible while still able to get a clear zoom on the coin. Photos were taken as Raw, the post-processed with Adobe Lightroom (free mobile version) by cropping in to the coin with a 1:1 aspect ratio and doing simple exposure / color adjustment (mostly the Auto setting).
The resulting pictures:
With the Macro lens:

Without the Macro lens:

The major advantage of using the Macro lens was that it allowed me to focus with the camera much closer to the coin. The closest I could keep focus without the lens was about 14 cm (coin to front of phone). With the lens it was reduced to about 10 cm, with about 7 cm from the front of the lens to the coin.
The resulting processed jpeg figure was 502 x 502 pixels (175 kb) without the macro lens and 1045 x 1045 pixels (738 kb) with the macro lens.
When reducing the file size to the same (about 100-200kb) for posting the photos appear similar, with a slight detail advantage (in my opinion) for the use of the macro lens. However, the full size image shows additional details for the macro lens versus no macro lens image, especially when zooming in.
Is the macro lens worth it for coin photography? In my opinion, additional factors (background, lighting, angle, focus, etc.) are likely to make more of a difference than the presence versus absence of a lens. Assuming you have a handle on some of those factors, I think the $55 lens does improve the quality of the coin images when done on a mobile phone camera. It is also possible that a new phone with a better camera would have better results.
On the other hand, for about twice the price you could start looking at used DSLR or early-generation mirrorless cameras and older generation used lenses. I'm not sure that the intermediate (cell phone lens) is worthwhile - you can get almost as good images without it, and it might be worth the additional investment for a major setup in in a separate camera.
Some other thoughts:
The lens is quite heavy and solidly made. This means that cheaper "cell phone" tripods or just laying the phone on a box or books (without a counterweight) will not work. I had to add some weights onto the phone to prevent it from tipping. I also found the clip interfered with part of the screen that was important for changing some of the photo settings, so I had to set the settings before attaching the lens.
I'd love to hear what thoughts other people have with low-cost clip on cell phone macro lenses for coin photography, as well as any tips and tricks for using them. I really wanted to have a small / light / portable lens that would make my cell phone usable for "in the field" coin photography.