Here is the full list of all 16 Hidden Corgi Mansion achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Find 10 Corgis
Find 20 Corgis
Find 30 Corgis
Find 40 Corgis
Find 50 Corgis
Find 60 Corgis
Find 70 Corgis
Find 80 Corgis
Find 90 Corgis
Find 100 Corgis
Find all outdoor toys
Find all the toys from the hall
Find all the toys from the winter garden
Find all the kitchen toys
Find all the toys from the bedroom
Find all the corgis and all the toys