Allow ICMP from whitelist .txt hosted online?

[CntrlAltDel]

Hi there,
Does anyone know if it's at all possible to source IP whitelist for ICMP from an online .txt? In GUI there's only a blanket "Respond ICMP Echo (ping) Request from WAN" option but I'd like to control this a bit more.

 

[CntrlAltDel]

Spent some time on this and took the most direct approach and it seems to be holding up:
- Installed Entware via amtm
- Installed curl and ca-bundle to download from https link with ip list .txt
- Created updater script that just curls once daily the .txt ip list
- Script then applied rule list

- Confirmed daily cron job
- Confirmed ICMP allowed for those IPs and not allowed from other sources (General "Respond ICMP Echo (ping) Request from WAN" is disabled).