there were no widespread commercial single-egg cookers specifically designed to function like a toaster for boiled eggs. However, it's worth noting that the kitchen appliance industry is continually evolving, and new products may have been developed since then.
At that time, preparing a single boiled egg was typically done using traditional methods like a pot of boiling water or specialized egg cookers designed for multiple eggs at once. Some microwave egg cookers also existed, but they were often designed for more than one egg.
If you are interested in a single-egg cooker, I recommend checking with kitchen appliance manufacturers, specialty stores, or online marketplaces to see if any new products have been released to meet this specific demand. Additionally, searching for "single-egg cooker" or "toaster for boiled egg" online might yield more up-to-date information on the availability of such products.