The are delisted for purchase but still available to download from Steam’s CDN for the Steam client. I own 3 delisted Transformers games but was able to reinstall them recently.

Tangentially related but even though the Nintendo 3DS e-shop has been shutdown for years you can still download your purchased games through your download history.

I was very happy just last week I was able to redownload Monster Hunter 3 Ultimate for my 3DS despite the store being down.

It gives me at least a little bit of confidence that having some games as part of a digital library on the Switch and Switch 2 will be easily available for the foreseeable future.