The US version supports full button customization. You can map the Genesis’s three-button or six-button layout to the Switch’s face buttons, shoulder buttons, or even the Z triggers.
Nintendo actively bans consoles that play unauthorized NSPs online. SEGA Genesis - Nintendo Switch Online -NSP--US-...
The official app requires a periodic online check to Nintendo’s servers to verify your Expansion Pack subscription. However, custom NSPs distributed by scene groups (like “Venom” or “SUXXORS”) often include a modified ticket or use signature patches (via Atmosphere’s sigpatches) that disable this check. This allows a hacked Switch to launch and play all included Genesis games indefinitely, offline. The US version supports full button customization