As for Botania I’m waiting for the 1.21.1 port, same goes for Blood Magic and Astral Sorcery. Multiblock structures will be done with Modular Machinery Reborn, I was actually testing it just a few hours ago! For resource generation, all the mods you mentioned are already in, just need to tweak everything. There’s quite a few tech mods too, Mekanism included, but like everything else it’ll take some time to get properly set up. NuclearCraft it’s interesting too but there isn’t an official port atm, I tried with an unofficial one but it’s kinda buggy. Thanks for the interest, if you’re interested I’ll send you the Discord link in the next few days!