[aasasd]

> However Chromium is open source and it's still impossible to do so.

I don't know if it's true that the official Chromium or Chrome don't allow sideloading at all—but the rather popular ‘Ungoogled Chromium’ build certainly does (in fact, it probably still doesn't work with the web store directly): https://ungoogled-software.github.io/ungoogled-chromium-bina...

However, the security of these builds may be questionable.

[Avamander]

You can absolutely load unpacked extensions on Chrome, it's just not as convenient.

[ajayyy]

Previously, you could load self-signed crx files as well. This doesn't require developer mode.

This was removed around a year ago.