The new version (v1.3) of Instant Campaign is now out with support for SDL Tridion Sites 9.1/9.5 and DXA 2.2.
It is available for download on the SDL AppStore: https://appstore.sdl.com/web-content-management/app/instant-campaign/748/

Instant Campaign makes it possible for digital agencies to create engaging campaigns with a rich experience without the need of creating custom templates in Tridion. The agency delivers the campaign as a ZIP file which is uploaded into Tridion. The Tridion editor can then edit textual content, images, links etc in the campaign. The campaign content can also be localized and sent for translation. The sweet spot for Instant Campaign is primarily for short-lived campaign pages and experience-rich product detail pages. But it can be used for any rich content to shorten the time to market without the need of involvement of IT to develop new templates.

Instant Campaign is free, open-source and is fully supported by SDL. You find the source code here: https://github.com/sdl/dxa-flexible-campaign-content