Firefox extensions are only available for Firefox on desktop (Windows, macOS, Linux) and Firefox for Android.

Blame Apple for their restrictions on what browser engine can be used on iOS/iPadOS as thankfully they do not have the same restrictions with web browsers on macOS. Firefox for iOS/iPadOS is basically a wrapper. https://support.mozilla.org/en-US/kb/add-ons-firefox-ios

However things may change thanks to the European Union (EU) is forcing Apple to allow other browser engines on iOS/iPadOS devices within the EU through the Digital Markets Act (DMA).

Default built in features on Firefox iOS will let you customize the homepage, but sadly the swag button is unavailable as he was saying in the earlier reply.