https://astrobites.org/ is great for astronomy and astrophysics. You'll be thrown out in the deep end but if you stick to it for a few weeks you'll get a good idea of where astronomy/astrophysics research is at.
We were in a similar situation a few months ago when Mitro announced that they were shutting down their service.
Mitro's owner being really nice, they open-sourced the browser extensions, server and mobile applications so we used them to run our own: https://passopolis.com/
We plan to keep the code open-source and we're working hard at the moment to introduce the organisation feature useful for start-ups. We plan to make the organisation feature a premium service so we can justify running and improving Passopolis for as long as it stays useful.