gvprtskvni The key matter is here: https://grapheneos.org/faq#future-devices
At the moment there are no devices that meet the security requirements that have those features. In general, very few devices with those features are being built by anybody. It appears that this is because the vast majority of users do not value those features, or at least not enough to offset increased costs or other problems. For example, removable batteries and SD slots make water resistance harder and more expensive.
The GrapheneOS project is not presently in a position to compel OEMs to add physical features that most users do not demand. It is difficult enough to find an OEM willing to meet the security standards.
The situation is similar to the situation with the very small fraction of iPhone users (probably under 1%) who intensely want a new iPhone mini. Those users absolutely exist, and they very much want what they want, but in Apple's judgment the costs would be greater than the benefits.
Please note that I do not speak for the GrapheneOS project.