How can I use Chrome on unsupported macOS 10.7.5 with an old computer?

You can use this, which was developed for 10.7 - 10.9:

Chromium Legacy built on Chrome 124 (not being updated further but fine for now):

https://forums.macrumors.com/threads/chromium-legacy-google-chrome-for-os-x-10-7-10-9.2283612/

or if you can use Firefox instead :

Firefox Dynasty (constantly being updated with build based on latest Firefox):

https://github.com/i3roly/firefox-dynasty ('Latest' download under 'Releases' lower right)

nah the app checks the envioment at launch, try firefox or brave or operate or other browsers which may not have as high requirements