Can I access my Google Backup and or my HTC Backup on my PC? On my old HTC One X+ (android 4.2) I've enabled both the htc backup and google backup via android's backup and restore.

Now I see that HTC's backup has completed and googles too, but is it possible to actually look at those backups?
Extract data from them on PC, etc?

Google Dashboard shows no signs of backups. I have an account at HTC which also does not allow to browse backups or even know that there are backups.

How am I able to restore information when a desaster happens? My photos are synced in google photos, fine but what's with the rest? My documents, my local data etc? Is there a way even to know which apps were installed (besides the data used by this apps)?

If for instance my phone breaks and I decide to not to buy a HTC again, what's my HTC backup's worth? And google?
For Google back up, you can check these sites from your computer's browser. Google Photos, Google Contacts. If you have manually backed up a file to Google Drive, you can go to Drive.google.com . All data that you see on these sites are the only data that can be backed up to Google.