I, for one, would be in favor of selling physical PC games on flash drives. Like, flash drives are (were? not sure how bad the chip shortage has hit them, if at all) dirt cheap, and even the biggest games today generally don't go far beyond 128GB (not counting post-launch patches), and I can find 128GB flash drives retailing for $10 right now at Micro Center. I assume a big enough publisher buying in bulk could get them far cheaper and more price optimized for this specific use case, and 256GB drives for even larger games for not much more. It would be more expensive than discs or cards, true; but not every PC has a disc drive or SD card reader, every PC these days has USB ports and most of them have USB 3.0 now. And still being smaller and more durable than a disc the same way cards are, could save on packaging costs if they optimized the packaging for it.

I also feel that people buying physical PC games are usually enthusiasts willing to pay a premium, anyhow, and giving them a reasonably nice flash drive with the game on it would feel more "substantial" than just getting a card or disc in a plastic case.

You can legally resell if it is on disk.

Tbh, popular indie games could probably use crowdfunding platforms post launch to do it

But a SD card with a custom label in box with proper box art and a little art book inside would be cool for fans and collectors.

Essentially Switch cartridges, but PC

Perfect. 👍