I doubt that changes in sleep due to COVID-19 infection would be novel enough to have a high enough sensitivity and specificity for diagnosis. It’s conceivable that COVID would worsen oxygen saturations during sleep in some patients, increasing the number of EEG arousals. But this would be the same for any other lung disease that compromises the respiratory system.
You would not expect to see anything specific for the disease. Sleep would be disrupted. Patients greater more REM when stressed. Arousals increase with desaturations but nothing specific to the syndrome just a constellation of changes that would vary from one patient to another.
diagnosis.confirmation of covid can only be done by microbiology. Sleep alterations are non specfic to any illness. The use of this as a suspicion to evaluate a patient further for covid is possible, but still warrants more evidence.