I used to do Capoeira regional while I lived in Philadelphia. I now live in Pittsburgh where the primary game is Capoeira Angola. One of the issues I'm running into is that my low game is not great. Most of our drills are upright, and that seems to be what the student leading the class (we lack a proper mestre) is comfortable teaching. Are there any drills for improving one's low game, sequences linking one movement to another while staying low?
Like any activity where you want to make those kinds of improvements; Visualisation is your friend. See yourself in your mind making those sequence links and keeping low. Do this over and over to get comfortable in your mind that you will be able to do the moves you want.
The other thing is flexibility and strength. Both can be worked on separately, holding the position you need to off the ground. Transitioning through the moves very slowly so that you get comfortable and strong at every inch of this movement.
Bryan Garrett proposed doing Benguela games. This might actually something you want to do. As Benguela was designed to help students of Capoeira Contemporânea to develop a low game that then can lead to the game played with toce de angola. ( https://pt.wikipedia.org/wiki/Benguela_(capoeira) ). Sequences always change and depend mostly on your teacher (and group). But remove all Jinga, only do Cadeira, Negativa, Role, different Aus (com e sin Cabeça no chão) and you got a solid basis of defensive moves you can combine to your own movements. Add to them kicks that always start from and end on the floor and you get more variety. Remember that different groups have different movements to the different toques. Maybe you should look up some workshops on weekends so that you can learn this part from another teacher.
I know you said you're training Angola,.. but have you considered trying CDO Miudinho sequences? From my experience, its a great way to rep ground movements.