The scale is correct, VR Tourviewer uses the physical FOV of the Quest 2. This is fixed and can't be changed in VR, changing it would cause instant nausea. This is because when turning your head 90 degrees in real life, the image has to rotate exactly 90 degrees too. If there's a difference between the physical rotation and the image rotation, nausea is easily triggered.
You can make a comparison with an equirectangular image from your tour by copying it to the Pictures folder on your Quest. Then in the bottom toolbar select Apps, then choose TV (top right) and select 'Your Media' to open your image.
You can then change the projection to 360.
I've tested this and the result is the same as in VR Tourviewer.
The perceived scale is influenced a lot by the camera height when the picture is taken. For example: if the camera is lower than your physical eye height, the world looks bigger. If the camera is higher, you feel like a giant. This is especially noticeable in interior images due to the closeness of the walls.