Is it permissible to delay washing the face when performing ghusl for janabah due to a skin sensitivity, and then wash it later as part of wudu, using a wet tissue for the affected area?

Your actions during the ghusl (ritual bath) are permissible: separating the ghusl, disrupting its order, and performing wudu' (ablution) to complete the removal of the major impurity are all fine, provided you do not intend to remove only the minor impurity without the major one. Washing the face with a mahramah (cloth) is permissible if the water flows over the entire limb. However, if the water is scant and does not flow, and you spread it with a mahramah, then this is masah (wiping), not ghusl, and ghusl is not valid except in cases of necessity. It is preferable to delay wudu' until the sunnah (prophetic tradition) dictates, but if you need to dry your face, there is no harm. The intention of completing the ghusl is sufficient for you, and there is no need to make a separate intention for wudu'.