@roelwolf made a fork of LMIC-node with support for GPS that is tested on the TTGO T-Beam v1.0 board and should probably also work on T-Beam v1.1 (latter is an assumption).
You can find more information about it here: LMIC-node | One example to rule them all - #20 by roelwolf
Note that the GPS extensions are not documented. You will have to check the source code.