To me it seems that OpenStreetView was made especially as an answer for Mapillary. Mapillary has almost 80 million photos uploaded by enthusiasts, who did it free charge.

Yet, even for a simple embed on a website, you have to pay them $99 / month. Using the images for custom maps: $249 / month.

Accessing the data is not publicly available, but is probably in the range of enterprise pricing options, only listed as "Contact Us". To me this seems to be the opposite of the OSM model and there is a huge need for a OSV like platform.

Exactly. OSV is totally about being Open and free (as in both freedom and price).

Can OSV/OSM contribute the same resources to their project as Mapillary is contributing to their own?

Mapillary is VC-backed. OSV is backed by Telenav, a publicly traded location services company. Your call as to which is the more sustainable model!

(The OSM Foundation has no connection with either project and is traditionally focused on its core task of collecting and distributing openly-licensed vector geodata.)

Is it free to use OSV images and data in commercial projects?

Images are openly licensed. Data licence hasn't been published yet but the project creators are making encouraging noises (e.g. in the comments thread of the linked post).

There's back and forth about that in the comments at the link. Note that 'jesolem' over there is the CEO of Mapillary.

The short answer is that if you sign up for a normal account and upload a photo to Mapillary, it appears for all other users on their website and is available in some OSM editors. Getting the complete raw data is not currently possible.

Mapillary also apparently offers private databases to users, those photos aren't available to the public. But those users aren't going to be naive to that fact, they are paying for the private instance.

Mapillary offers free bulk access to the imagery, but with the catch that the location metadata is excluded(!). This makes the bulk image access effectively pointless. OpenStreetView seems to have every intent of opening bulk access to both the imagery and the metadata; which will finally make it useful.

You can get that metadata through the APIs.