It depends on the storefront, so be careful with "Apple allows it now".
- US App Store: after the 2025 court ruling, apps may include buttons/links to buy on the web, without Apple's commission. So "Subscribe" → opens your website → Stripe Checkout is allowed there.
- Elsewhere: digital subscriptions sold inside the app generally still have to use In-App Purchase, with regional exceptions (EU has its own alternative terms, with fees).
A Stripe Checkout in a webview inside the app is the thing most likely to get rejected. Open it in the external browser instead, and gate by storefront if you ship worldwide.
Many people end up doing both: IAP in-app, plus web purchase, and something like RevenueCat to unify entitlements.