Yes, I agree. Both are interested to see VR growing as a whole, and to release their game on other platforms would give them more revenue. I only expain why they keep stuff exclusive: because their main revenue are games being sold in their store.
Sony's idea with PC ports is to get extra revenue for old games and to reach PC players who may end buying a PS5, but specially those who are PC only players, specially in countries where for many reasons (taxes for foreign electronics, being too expensive, market too used to F2P, rampant piracy, tradition of playing on PC instead of in console, etc) consoles aren't so popular and instead PC is.
Specially Asian ones like China or Korea and a few South American ones. Asia is the biggest gaming market in the world and the one with biggest growth. Latin America is growing a lot too. For that same reason Sony is also exploring mobile (generates worldwide more revenue and has more players than PC and console combined, and again primarly in Asia) and GaaS/F2P (again, more revenue and players than non-GaaS/paid games and specially in Asia).
They don't care about closed or not ecosystems: they care if the market is big enough or not, and what revenue (both total revenue and percentage of revenue share) are they going to generate there. This is why they have their own closed platforms and if you want to publish games on their platform you have to pay them both to enter and both a revenue share of the games, and also why they publish their games on Windows on PC even if they prefer to use their own OS instead of Microsoft's one for their devices.