Question about location of older apps no longer available in the app store

There is no official repository of old iOS apps. Contact the developer and ask them. There’s a high likelihood that an older app will not be compatible with newer hardware. Do you have access to older iPhones?

It depends upon where you live and who is making them available.

Learn more about alternative app marketplaces —> About alternative app distribution in the European Union - Apple Support

and this post by etresoft https://discussions.apple.com/thread/254809174?answerId=260248219022#260248219022

"Safely" is a matter of perspective.