Old Android phones for app testing (Woolwich SE18)

I'm a software developer in London looking for unwanted Android smartphones to test an app across different real devices and Android versions.

Old, slow or cosmetically damaged phones are fine - cracked screens, worn batteries, damaged cameras/back glass etc are not necessarily a problem.

Main requirements: powers on; can connect to Wi-Fi; isn't locked to somebody else's Google account/FRP locked; can install and run apps.

Especially interested in phones sitting unused in drawers. Happy to collect locally. Would also consider very cheap devices or several old phones together.

For software testing, not resale. Thanks!