To answer your question: yes keyless works without the accelerator as well, but it is still under development; will be available for the official public launch.

Lets differentiate the accelerator from a plugin or API that has to be installed on the website you wish to visit as a user/visitor: The accelerator is installed on the users/visitors side and it is not and API/plugin to be integrated in let's say on each wordpress sites.

I would suggest to actually trial the product and see how it works.