There are loads of better ways to do this using Google Search Console / Bing Webmaster Tools / ahrefs and similar tools.
Arguably these might be a bit too much for a small side project or a curious quick check, so this is how I do it. The same syntax works for both Google and Bing.
"tech-playground.com" -site:tech-playground.com
Effectively this searches for my domain and excludes all matches on said domain.
It is not perfect for domains with - in them since that gets excluded from the exact match,
but it get’s the job done good enough.