You can merge armatures and meshes. There are a few questions and answers about this if you search for "merge armature" for example this one: Joining 2 Armatures and keeping the weights.
But I guess, there is no need for this and you can get away by just using the body's armature for the gloves. While the glove's armature seems to have no bones for ...
In the modifier you can enable the On Cage option and, in Edit mode, the mesh will appear as it is when posed (even though the gizmos will stay at the non-modified position, which is unfortunate imho):
If you want your mesh to definitely take the Pose position and don't need anymore armature, apply the Armature modifier.
If you want to keep the armature and ...
If you move the joint, bones have to stretch along their Y axis. This behaviour can be obtained with this setup, in which every deforming bone has one constraint to copy the location of a control bone and another constraint to stretch to the following control bone.
You need to manually paint weights values of 0-1 in weight-paint mode. There is no easy way to go about it besides the automatic-weights assignment which you'd already stated as invalid for this scenario. Additionally, make sure that your mesh has no double (overlapping) vertices.