The full-frame Foveon saga has been going on since 2018 when it was first mentioned at Photokina during the Sigma, Panasonic and Leica L mount alliance. It was originally expected to be released in 2019, but in March 2019, this was revised to 2020. Only a day after rumours of a February 2020 release, Sigma announced that they’re still working on it and the following month its release was delayed until at least 2021, but probably 2022.
At the beginning of 2021, that release date target became 2023 and now it seems that Sigma might be on track. In a recent interview with Sigma CEO Kazuto Yamaki, he reaffirmed that Sigma is still working on prototypes of the full-frame Foveon X3 sensor and that it “should be available sometime this year”. The way it’s worded sounds like the sensor will be available, but perhaps not in a retail-ready camera.