Importing a generated mesh into Blender takes one menu item. Getting it to a state where you can work on it takes about five minutes more, and almost all of that time goes on the same four things every time.
This is those four things, in the order they bite.
Import the GLB, not the OBJ
File > Import > glTF 2.0 (.glb/.gltf). Blender has read glTF natively since
2.80 and it is the format that arrives with its materials already wired into a
Principled BSDF. Nothing to reconnect.
The OBJ will import too, and it will look correct if you kept the .mtl and
the texture files next to it, but the MTL material model predates PBR by two
decades, so what you get is an approximation you will end up rebuilding. Take
the GLB unless something specific stopped you.
If the model looks grey after import, you are in Solid viewport shading. Press
Z and pick Material Preview. This is the single most common "the textures did
not come through" that is not actually a problem.
Fix the scale before you do anything else
A generated mesh has no idea how large the real object was. One photograph carries no measurement, so what you get is a model with correct proportions and arbitrary size, usually somewhere between one and two Blender units on its longest axis, whatever the subject was.
That matters more than it sounds. Blender's default clipping, the size of the default light, and every physics and modifier default assume a scene in metres. A chair that imports as two units tall is fine; a chair that imports as two hundred is a scene where nothing behaves.
Set the size you actually want in the N-panel dimensions, then
Ctrl+A > Scale to apply it. Applying matters: leaving a non-uniform scale on
the object makes modifiers and later exports behave in ways that are annoying
to debug.
Move the origin to somewhere useful
Generated meshes usually arrive with their origin at the centre of the bounding box, because that is where the reconstruction put it. That is the wrong place for almost everything you will do next: placing it on a floor, rotating it, snapping it to a socket.
Object > Set Origin > Origin to Geometry gets it to the middle of the mesh
rather than the middle of the world. To get it to the base, put the 3D cursor
where you want the origin (snap it to a selected vertex with Shift+S), then
Object > Set Origin > Origin to 3D Cursor.
Two seconds now, or a rotation about the wrong point every time afterwards.
Then deal with the topology, if you have to
Here is the part worth being honest about: a generated mesh is triangulated and dense, and the density is uneven. It is built to look right from the outside, not to be worked on.
Whether that is a problem depends entirely on what happens next.
If it is a static prop, it is not a problem. Add a Decimate modifier in Collapse mode and pull the ratio down until the silhouette starts to suffer. Most generated props survive going to a fifth of their triangles without anyone noticing, and a game engine will thank you.
If it has to deform, it is a problem, and decimation will not fix it. A triangulated mesh with uneven density does not bend cleanly at a joint, and no amount of weight painting rescues it. You want quads with edge loops running the way the thing bends. Blender's QuadriFlow remesher gets you most of the way for an organic shape; for anything hard-surface you are usually better off using the generation as a reference to model over than trying to repair it.
That is not a criticism of the generation. It is what a reconstruction from a photograph is: a surface, not a topology.
Two smaller things
Shading looks faceted. Right-click the object and Shade Smooth, or
Shade Auto Smooth if you want the hard edges kept. Generated meshes almost
always want auto smooth, because they have both.
Something is inside out. In Edit mode, select all with A and hit
Shift+N to recalculate normals outward. This is rare on a generated mesh but
it does happen where the reconstruction had to close a surface it could not
see.
What to do about the texture
The GLB arrives with a baked texture, which is a result rather than a source. If you intend to relight the model, change its surface, or match it to other assets in a scene, download the PBR map set separately instead (base colour, normal, metallic-roughness, ambient occlusion, emissive) and build the material from those. Wired into a Principled BSDF, that is a material you can actually art direct.
If you are only placing the prop in a scene and moving on, the baked texture is fine and you should not think about this again.
The honest summary
Import GLB, set the scale and apply it, move the origin, decide whether the topology matters for what you are doing. Four things, five minutes, and then it is just a mesh like any other.
Everything above is true of any reconstructed mesh, not only ours. If you have worked with photogrammetry output before, none of it will be new. The failure modes are the same because the problem is the same one.