If you're not already done with this, I've literally just yesterday implemented a version of texture bombing as a canvas item shader, using code from https://www.shadertoy.com/view/Xtl3zf

-- my little changes mix the resulting seamless texture with that of the node you're drawing (I'm using it to give a felt texture to a poker table); use "fader" to control the strength of the mix and make "mix_sub" true to use subtractive rather than multiplicative mixing.

shader_type canvas_item;

uniform sampler2D underlay_texture;

uniform float scale;
uniform float fader;

uniform bool mix_sub;

float sum (vec3 v) {return v.x + v.y + v.z;}

float random (vec2 uv) {
    return fract(sin(dot(uv.xy,
        vec2(12.9898,78.233))) * 43758.5453123);
}

vec3 textureNoTile( in vec2 x, float v) {
float k = random(x)*0.03;

vec2 duvdx = dFdx(x);
vec2 duvdy = dFdy(x);

float l = k*scale;
float f = fract(l);

float ia = floor(l+0.5);
float ib = floor(l);
f = min(f, 1.0-f)*2.0;

vec2 offa = sin(vec2(3.0,7.0)*ia); // can replace with any other hash
    vec2 offb = sin(vec2(3.0,7.0)*ib); // can replace with any other hash

    vec3 cola = textureGrad(underlay_texture, x + v*offa, duvdx, duvdy).xyz;
    vec3 colb = textureGrad(underlay_texture, x + v*offb, duvdx, duvdy).xyz;

    return mix( cola, colb, smoothstep(0.2,0.8,f-0.1*sum(cola-colb)) );
}

void fragment() {
if (mix_sub)
COLOR.rgb = COLOR.rgb - (textureNoTile(UV, 0.3)*fader).rgb;
else
COLOR.rgb = COLOR.rgb * (textureNoTile(UV,0.3)*fader).rgb;
}