Short answer: Of course!
Many angel groups require you to submit through Gust because it offers a consistency and makes reviewing applications easier. But not all use Gust same as not all use AngelList... I haven't met an angel who frowns upon using multiple platforms.
I would encourage you to leverage your twitter and Facebook or Instagram to meet angels and get in their radar (don't hassle or stalk) just try to get exposed a bit to them by being part of the same meetup group, follow the same blog, membership... Subscribe to their own blog.. And when you submit funding request considerations do please send a follow up email or a call or basket of fruits if you have contact them before.
