fediEngine is a Free and Open Source (GPLv3 licensed) desktop client for ActivityPub and related projects such as Mastodon, Pleroma, and Misskey. It is written in Python and PyQt5, isn't a web browser, and because it's not a web browser, it uses a lot less memory than a web browser, even with tens of thousands of statuses loaded.
fediEngine is designed to give you a complete view of the fediverse, one free of the restrictions and inefficiencies of normal server-to-server federation. fediEngine dynamically fetches statuses both directly from the servers they originate from, and from any servers they federate with. It also enables you to instantly view any instance's public or federated timelines, and search every instance at the same time.
Because the designer of a specific fediverse daemon gaslights users and calls that "security", fediEngine goes above and beyond to protect user safety and security. Powerful content-shaping utilities, some of which cannot be found on any other client, are here to provide you the security you've been begging Eugene to give you for literally years! List subscriptions, dynamic lists, and better tunable block logic keeps out, what you want out.
I already told you. Python and PyQt5.
The code is currently shittier-than-alpha quality. Follow the development/testing announcements account for links to each pre-alpha release. They happen about every two weeks.
An open alpha, including a public git repository, will happen once the internal structure is more solid.
No. You may import or subscribe to lists to block on an automated basis. You can also mark any instance as "excluded", which entirely prevents communication with, or the processing of information regarding, an entire instance.
If you are concerned about people using your computer to log into sites you don't like, you should put a password on that computer.
Letting you import your own list is more flexible.
fediEngine is licensed under the GNU General Public License, version 3. Section 12 of the GPLv3 specifically prohibits the surrender of anothers' freedom. A login block impedes "Freedom 0", or the freedom to run the program as you wish, for any purpose. Thus, a login block is not compatible with the GNU GPLv3.
Please keep in mind that while the GNU GPLv3 permits you to change the software and distribute your changed software to others, it specifically forbids the addition of restrictions on using the software. To make it clear, a fork of fediEngine that includes a login block would by definition be a violation of the license terms, and would terminate all rights you have to use or convey the software.
That's not how anything works. But, if it was, I feel like going after OS manufacturers might net you better results ¯\_(ツ)_/¯