Is your feature request related to a problem? Please describe.
Bulbis phycelium and ivis, nightshade and shulkren phylium cannot be spread onto end stone by using bone meal on the end stone, nor can they spread on their own like grass. This makes them non-renewable, makes terraforming with them require destroying swaths of End to acquire the blocks, and makes bald spots created by growing trees on them unable to be patched without transplanting in new blocks from elsewhere.

Describe the solution you'd like
You could let bone meal be used on end stone that is next to bulbis, ivis, nightshade or shulkren phylium to turn the end stone into the phylium in question. In the case of multiple, different adjacent phylium, a random one would be chosen to turn the end stone into. This would mirror vanilla nylium behaviour, as well as the behaviour of the ground types added by Better End. Speaking of which, the implementation should be compatible with Better End so that, if multiple BYG and Better End ground types are adjacent to end stone, it will correctly choose one randomly to turn into, instead of favouring one mod or the other or crashing or something.

Describe alternatives you've considered
You could also let the phyliums grow like grass to nearby end stone, and come up with something to prevent them from overgrowing end barrens/midlands/highlands/small islands biomes, as, otherwise, these biomes would quickly turn into phylium from an adjacent biome. I'm pretty sure this concern with the nether wastes biome is what made Mojang make nyliums require bone meal to spread.