And yes, you can add any blog.
For more see:
To export you subscriptions there is a not-well-documented XML export page
Company focus on Influencers
The company behind Bloglovin' is focused on their influencer network "Activate" more than blog readers (TechCrunch: Bloglovin’ becomes Activate). Activate was later acquired by Impact, a marketing company. The suggested blogs to follow on Bloglovin' are primarily lifestyle blogs.
The site's last Last official blog post is from 2017 suggesting Bloglovin as a product is no longer a priority. Furthermore, all of the top people on the about page show on LinkedIn that they left the company in 2017.