If you are having issues running Sonic Adventure 2 on Steam with Virtual Handheld, you may try the SA Mod Manager. The Mod Manager includes patches that may improve compatibility.

Note that the SA Mod Manager is not hosted or maintained by the developer of Virtual Handheld. Use at your own discretion.

For easier installation, you may want to exit VR and use your desktop to complete the installation.

Get SA Mod Manager here and follow the install instructions:
https://gamebanana.com/tools/15436

Alternate download page:
https://github.com/X-Hax/SA-Mod-Manager/releases

If you have further issues, the best way to get in contact is via my discord server:
https://discord.gg/NuPk9m9XeC