No dgl currently can not handle non-numerical features.
If you need to store discrete attributes (e.g. user, word, …) you can first turn them into index (integer).
It seems in your case, each node has a variable-length sequence. My suggestion is that you do not have to store the features on DGLGraph but process them outside of the DGL (e.g. use an RNN/LSTM to get a fixed-length feature of each sequence).
If you need to explicitly model the interactions between two items belonging to the sequence of different nodes, I recommend you to split each node into several nodes where each node represent a single item in the sequence, and build a new graph upon these nodes.