But they're not. You can very well have the swap on top of LVM on top of LUKS. And the root and other partitions share that same LVM and LUKS. So now you have FDE and the kernel will know how to assemble it all. The only difference with the default pop OS install is that the swap key isn't changed on every boot. But since the other partitions holding the actual data use persistent keys, that doesn't look like much of an issue to me.

Plus, if you're OK with using a TPM, you can also get waking up from hibernation without having to enter type in your password.

Source: been doing exactly that (without the TPM part) on a laptop for a few years, and it just worked like a charm. No hoop-jumping involved or anything.