I know this post is old but for those who are still seeking ways to tether with a restricted carrier here's another option:
https://www.technadu.com/how-to-share-a-vpn-connection-on-android-without-root/258827/

Note that this option doesn't work if you can't turn on hotspot at all.

Also, a few things not mentioned on the article:

  1. make sure to manually select an IP address for the http proxy from the app's settings besides 0.0.0.0, otherwise connected devices can't find the internet. (This may be a GrapheneOS-only thing)
  2. it also routes DNS traffics if you enabled Private DNS on your phone.

Again, not confirmed with T-Mobile but hope somebody finds this helps.

    GrapheneOS The way I understand it is that if you raise TTL by 1 on a Laptop connected to a GOS device hotspot you have to remove the "dun" parameter from the APN.

    If that's correct why is this the case? Why do I have to remove "dun" then?

      LKnet
      Also make sure to allow local lan connection if you're using a VPN defaults to block it (i.e. Mullvad).

        a month later

        LKnet
        AlanZ

        Confirmed using Every proxy app to bypass hotspot limit with T-Mobile. I didn't use a VPN (although I will be trying that next).
        My Path -
        T-Mobile Cell Service
        Pixel 8 Pro
        Every Proxy
        Mobile hotspot
        Windows 11

        Without every proxy, I got exactly 600kbps using testmy.net to test download speed. (My tether limit was exceeded this morning and I was warmed by text I would only get 600kbps)

        With every proxy, I got 155mbps.

        So, great success for me. I don't yet have GrapheneOS though so I can't say how that would affect things. Currently using OEM OS...

        Thanks for the help, LKnet

              mbsill

              Did you have to do anything on the Windows PC (adjust TTL, so on)?

                I solved this issue real easy. Just used a VPN. Make sure it's a VPN that does not leak DNS.

                  2 months later

                  If you want to remove throttling on a windows computer all you need to do is open command prompt as administrator and then type in this command netsh int ipv4 set glob defaultcurhoplimit=65 . Im using Verizon and not getting any throttling at all.

                  If you want to configure your phone so it does this automatically it wont be possible with grapheneOS or any device on Android 14.

                  In order to get this to work I downgraded to Android 13 the oldest official version I could find from google and then rooted the device with magisk. I then installed the magisk TTL module and now any device that connects to my hotspot bypasses the limits. I did this yesterday and it's working 100%. This is with a Pixel 7 using an MVNO on Verizon's network.

                  However this opens you up to all types of vonorbilties as the boot loader is unlocked. In my case it doesn't matter because it is being used as a backup modem in PFSENSE for my main fiber line but if you are using the phone as your primary phone it could easily be hacked.

                  If anyone needs help with this setup let me know

                  GrapheneOS So if we remove the DUN from the APN configuration it would be the same as changing TTL to 65 or 64 or whatever is working for the provider in question.

                    4 months later

                    locked i always notice how smart your posts are. do you have any more info on this? or are you being obtuse to let people know there's a way bu they need to figure it out and you don't want to post all info?

                        angela nevermind, figured it out!

                        there is no way at all ;-)

                          I'm using hotspot in T-Mobile but I either connect Samsung tablet to it or router with OpenWRT. And then connect my various computers (including Macbook) to router.