I investigated:Both are lateral flow, point-of-contact blood...

I investigated:
Both are lateral flow, point-of-contact blood tests that give results (detecting the presence of COVID-19 antibodies in the blood, signifying exposure and/or immunity to COVID-19) in under 15 minutes without the use of additional machinery. The CDY test is Chinese, has been in use for some months and is TGA-approved for use in Australia. There are questions over how useful antibody testing is, both in detecting infection and in confirming immunity, but if you accept that rapid antibody testing is useful (I don't, yet), then the CDY test does seem to be, if not the market leader, certainly as good as any other. This is one area where I suspect being Chinese gives credibility - they have, after all, known the disease longer than anyone else.
The Atomo test is Australian and 3 weeks ago I don't think it even existed. It uses what I regard as a gimmick, a built-in finger pricking method that qualifies it as a "self test". Once the blood is applied to the test strip, I suspect the technology is the same as the CDY one, or at least Atomo hope it is. However, it does not appear to be TGA-approved and self tests for COVID-19 are illegal in Australia, I believe. The reasons for that should be obvious - doing a test you don't understand for a disease you don't understand that gives a result you aren't trained to interpret, is a classic example of GIGO. Atomo has a French client which has bought all they can produce (sauve qui peut).
Both companies have other strings to their bows and in my view I would look to those other strings for reasons to invest in either.