Correct, up to storage limits.
That's not a minor consideration from me as I can easily fill 64--128 GB of total storage (about 30GB seem to be system + apps).
That's not all books --- I keep a fairly large number of podcast episodes downloaded. But at about 5 MB/book, even an apparently generous storage quickly shows limits.
I passed on the ReMarkable as its 16 GB storage (about 8GB available) only permits 1,600 books at 5 MB/book.
(And that's without podcasts or audio.)
The BOOX has a 64 GB onboard storage, maximum. I've got that near capacity in about 6 months, though a large share of that is podcasts. My preference would be 256 GB. Plus far better content-management capabilities on the device itself. I think I could live within that.
Retail cost is $20, falling by about half every 2 years. The minimising of eBook storage makes absolutely no economic sense.
