Something I still miss is a free and easy PDF tool which lets you delete, reorder and add pages from multiple PDFs. On Windows there is just Xodo but its UX is unfortunately subpar and on macOS you have Preview where the UI is better but once you have multiple PDFs from where you get the pages it can get confusing.
On Linux there is https://github.com/pdfarranger/pdfarranger
It has a nice UI and is pretty easy to use.