Omkar2118/datasets huggingface dataset:
MegaScale

Results of a high-throughput biological assay measuring the stability of proteins
https://github.com/Rocklin-Lab/cdna-display-proteolysis-pipeline
From the paper "Here we present cDNA display proteolysis, a method for measuring thermodynamic folding stability for up to 900,000 protein domains in a one-week experiment. From 1.8 million measurements in total, we curated a set of around 776,000 high-quality folding stabilities covering all single amino acid variants and selected double mutants of 331 natural and 148 de novo designed protein domains 40–72 amino acids in length. "
This assay have some particular limitations such as the small size of amino acids, and the particular way stability is measured which is expected to be correlated to typical assays for thermostability . Its advantage is that it contains orders of magnitude more  mutants among existing thermostability datasets (typically 100-1000s mutants for tens of different proteins)