While dated, in the world of covid (September) this is a great article on what may be the only jurisdiction in Canada using a saliva based test .....a great read on a Sunday morning.
https://www.cbc.ca/news/health/saliva-testing-reopening-covid-19-1.5727732
To summarize, the test sample is easy to obtain, although it does require an adult (currently used for children), and it's accuracy appears to be equal to the swab test. Two issues which still prevail under this test and which Therma Bright and Orpheus are focusing on is cost and time.
The test presented in the article must still be sent to a lab and still requires relatively expensive reagents during analysis. As a consequence test results can take days to acquire.
The end of week jump in sp and the tweet, combined with the fact that Therma Bright and Orpheus May not be as far behind the curve as could be derived from this article and by some on this board is good news. There does not appear to be any news about any other saliva based test being ready for clinical use. This week could be a significant turning point for everyone including Rob Fia who has devoted time and significant resources out of his own pocket to support this company.