Bought my niece a book ('The Hobbit') for her birthday and figured that I'd pair some Lego with it, considering her age class, but couldn't find a single (affordable) Lego tie-in. So I tried 'Lord of the Rings' instead, same story. Then I tried 'Rings of Power' as a last resort, and the only results were 'Lord of the Rings' tie-ins, rofl.
You can buy a shitty plastic Gandalf pipe to smoke some Shire weed (left over garbage from The Hobbit era), but not a single 'Rings of Power' piece of merchandise.
The Harry Potter franchise on the other hand is still going strong. They're even releasing new Lego kits each year, although each of them is paired with a little Harry Potter Lego figure, resulting in a Harry Potter clone army if you are foolish enough to buy them all as gifts.
Lego doesn't think that LotR can carry a full lineup by itself, so they only release big sets for collectors. I hate it, because they did used to make very cool playsets for cheap but they've been out of production for so long the prices are ridiculous.
And then some.