Just in case you see this, but you don't actually have to do Imperial Devices at all to join a Grand Company or to get your Chocobo. You have to do all the other quests and if you need more seals you can do the L30 company leves, the company quests around town (they are in or around the guilds), or if you have any NM drops you can turn those in.

Also, if you do end up going into toto-rak, the drops there can also be used for seals.