Create a cubemap at runtime from a downloaded 360 texture

After a few more hours of research, I came across this thread which contained a shader which allowed to me accomplish what I was looking for:

https://forum.unity.com/threads/equirectangular-background-shader.364287/

It's a shader that can be used as a skybox material which takes a latlong texture. Here's the code, credited to bgolus of the Unity forums:

 Shader "Skybox/Equirectangular" {
 Properties {
     _Tint ("Tint Color", Color) = (.5, .5, .5, .5)
     [Gamma] _Exposure ("Exposure", Range(0, 8)) = 1.0
     _Rotation ("Rotation", Range(0, 360)) = 0
     [NoScaleOffset] _Tex ("Panorama (HDR)", 2D) = "grey" {}
 }
  
 SubShader {
     Tags { "Queue"="Background" "RenderType"="Background" "PreviewType"="Skybox" }
     Cull Off ZWrite Off
  
     Pass {
      
         CGPROGRAM
         #pragma vertex vert
         #pragma fragment frag
  
         #include "UnityCG.cginc"
  
         sampler2D _Tex;
         half4 _Tex_HDR;
         half4 _Tint;
         half _Exposure;
         float _Rotation;
  
         float4 RotateAroundYInDegrees (float4 vertex, float degrees)
         {
             float alpha = degrees * UNITY_PI / 180.0;
             float sina, cosa;
             sincos(alpha, sina, cosa);
             float2x2 m = float2x2(cosa, -sina, sina, cosa);
             return float4(mul(m, vertex.xz), vertex.yw).xzyw;
         }
      
         struct appdata_t {
             float4 vertex : POSITION;
         };
  
         struct v2f {
             float4 vertex : SV_POSITION;
             float3 texcoord : TEXCOORD0;
         };
  
         v2f vert (appdata_t v)
         {
             v2f o;
             o.vertex = mul(UNITY_MATRIX_MVP, RotateAroundYInDegrees(v.vertex, _Rotation));
             o.texcoord = v.vertex.xyz;
             return o;
         }
  
         fixed4 frag (v2f i) : SV_Target
         {
             float3 dir = normalize(i.texcoord);
             float2 longlat = float2(atan2(dir.x, dir.z) + UNITY_PI, acos(-dir.y));
             float2 uv = longlat / float2(2.0 * UNITY_PI, UNITY_PI);
             half4 tex = tex2D (_Tex, uv);
             half3 c = DecodeHDR (tex, _Tex_HDR);
             c = c * _Tint.rgb * unity_ColorSpaceDouble.rgb;
             c *= _Exposure;
  
             return half4(c, 1);
         }
         ENDCG
     }
 }  
  
  
 Fallback Off
  
 }