I wonder how safe is it to whitelist honorable VPN service provider's IP (for example NordVPN) in, for example Azure/AWS to use RDP/SSH? Is it any better then whitelisting local ISP's IP assigned to me?
While restricting the address space that is allowed to access the ports is always a good idea, both your options are equivalent, generally speaking.
If your local ISP has as many customers as the VPN provider - or both numbers are in the same ballpark - you have equivalent security gains if the ISP uses an IP pool where you regularly get a new IP from that pool. There's one thing to consider though: VPN providers allow access from everywhere for basically everyone who wants. This is either a pro for you while you travel and do not have an IP from your local ISP assigned or a pro for an adversary that is not able to get service from your local ISP.
If restrictions on the ACL are so wide, either way, you should still consider the ports public and use public key authentication rather than password authentication and keep your machine up to date.
If you only use the currently assigned ISP's IP or if your ISP does not use a pool, you'd be better off using that IP to whitelist.
If you need to access the services while away, you might host a VPN proxy in your home network