When searching for adoptees' potential biological relatives, DNAGedCom is an absolute must. https://www.dnagedcom.com/
Unlike GedMatch which requires downloading raw data by contributors, this site collects matches (rather than raw data) directly from FTDNA, 23andMe etc. and numbercrunches it. This means it includes data from samples from all those disappointed by their DNA findings, or deceased, who are unresponsive.

Keep safe;

Nicole Heymans, near Brussels, Belgium