Robust, sensitive, and specific diagnostic platforms for early pathogen detection are essential for the identification of infected patients and management of current and future pandemics. CRISPR-Cas systems have been repurposed for SARS-CoV-2 detection in two-pot assays. Two-pot assays require extra steps and are prone to cross-contamination; however, the temperature range of current Cas enzymes limits the development of one-pot assays Here, we characterized TccCas13a, a thermophilic Cas13a enzyme with cis and trans activities from 37-70°C, and HheCas13a, which had a limited range and lower activity. We harnessed TccCas13a in a one-pot SARS-CoV-2 assay with two layers of amplification and TccCas13a-mediated collateral degradation of a single-stranded RNA reporter. This assay showed 95% sensitivity and 100% specificity compared with RT-qPCR on clinical samples. We also developed a mobile phone application to facilitate data reading, collection, and sharing. Our OPTIMA-dx detection module exhibits key features for point-of-care SARS-CoV-2 screening and pathogen detection in general.