MikroTik Secure Internet Connection Setup with OpenVPN user management

In an area that have not internet I have a mikrotik hap ax3 which ether1 is connected to the internet through starlink while the ether2 is connected to the router that is connected to the area that have no internet, now i have other devices in the area which have no internet and looking to connect them to the internet, how i can do that securly, i have a cable to connect the router to the mikrotik on ether2 The router have static ip address details as below( APN Name: IP Address:178.131.84.28 Subnet Mask:255.255.255.255 Default Gateway:178.131.84.28 DNS Server:10.104.88.8 10.104.88.9) I have also mullvap vpn wireguard details and the devices want to connect it will use lt2p and openvpn and they are on different network thatn the router but in the same area that have no internet but they can ping the router, the router is provided by ISP in area that have no internet, the router have static ip address to allow user connected on other devices without interruption as if it was not static ip address the IP address would be updated and causing the devices disconnection

OpenVPN user management with specific size and limit and time like 1 ,2 ,3 gb for 1 week

INTERNET (UNRESTRICTED)
│
┌─────────────┐
│ Starlink │
│ (Public Net)│
└──────┬──────┘
│
ether1
│
┌───────────────┐
│ MikroTik │
│ RouterOS │
│ │
│ WG (Mullvad) │◄─────── VPN Tunnel
└──────┬────────┘
│
ether2
│
COUNTRY / INTRANET NETWORK (RESTRICTED)
│
┌───────────────┐
│ WiFi SIM │
│ Router │
│ (192.168.50.1)│
└──────┬────────┘
│
┌──────────────┴──────────────┐
│ │
┌──────────────┐ Mobile Users / Devices
│ OPEN VPN / L2TP │ (Inside Country)
│
│
└──────┬───────┘ │
│ │
└────────── OpenVPN ────────────┘
│
▼
┌───────────────┐
│ MikroTik │
│ (Gateway Out) │
└──────┬────────┘
│
Mullvad VPN
│
▼
Internet