SIM should not matter. What will matter is the quality of your VPN/proxy. Most proxies and VPNs are misconfigured or not properly configured for the desired end results. The entire purpose of a proxy is to lie about your location within the network, in this case the internet. A VPN adds encryption and other capabilities to this. I would recommend you use a VPN for what you are trying to do. A VPN will treat the in-between as though it does not exist and to pretend that the two remote devices are in the same network, or on a network that can communicate "directly" to one another. A remote network may know that you are remote to it, but it will treat you as though you are local-ish. This is what VPNs and to some extent proxies do. If your VPN is properly configured it will strip your localized information and run outside traffic such as the internet through the far side, hiding your localized information from the wild wild web. Making sure your VPN or proxy are capturing the correct protocols is a trial-and-error scenario.
- You could pay for exit nodes. (still have to properly configure things)
- There are some services, such as McAfee that have proxy/vpn options and they allow you to choose your exit node country. Very handy if everything you are doing is legal. ProtonMail offers ProtonVPN as well. (may have less configuration options)
- You could also use Tor. If you use Tor, be very patient with the bandwidth. Also, sometimes Instagram may flip out. Oh, and be sure that all of your traffic is going through Tor (a little more difficult than one may believe). On phones, you would probably want to try TorBrowser. (Not a solution if you want to use an app other than a browser app.)
- My personal favorite is Orbot. Orbot requires more configuration but you are not stuck in a browser and you can use the VPN Mode for Full Device VPN, then select the apps you want to be in the VPN. The Android version of Orbot has a simple drop-down so you can choose your exit node country.