Is it possible to combine token replacement and string?

Thought about the same but in a different way.

For the example above

[node:field_hero_image:entity:field_media_image:og_image|"/themes/custom/my_theme/image.png"]

why not extend it like that:

[node:field_hero_image:entity:field_media_image:og_image|site:base-url"/themes/custom/my_theme/image.png"]

I think this could be achieved by adding another condition in TokenOrTokensPreAlter::tokensPreAlter:

diff --git a/src/TokenOrTokensPreAlter.php b/src/TokenOrTokensPreAlter.php
index f57cace..0d34def 100644
--- a/src/TokenOrTokensPreAlter.php
+++ b/src/TokenOrTokensPreAlter.php
@@ -44,10 +44,16 @@ class TokenOrTokensPreAlter {
         $sub_tokens = explode('|', $match_clean);

         foreach ($sub_tokens as $sub_token) {
+          $sub_token_matches = [];
           if (substr($sub_token, 0, 1) === '"' && substr($sub_token, -1, 1) === '"') {
             // This is a string replacement.
             $result = substr(substr($sub_token, 1), 0, -1);
           }
+          elseif (preg_match('/([^"]*)"(.*?)"/', $sub_token, $sub_token_matches)) {
+            // This is a token replacement with an appended string.
+            $result = $this->token->replace('[' . $sub_token_matches[1] . ']', $data, $options);
+            $result .= $result ? $sub_token_matches[2] : '';
+          }
           else {
             // This is a token replacement.
             $result = $this->token->replace('[' . $sub_token . ']', $data, $options);

@captain hindsight I think your solution could work. Feel free to create an issue fork to test that out.

@captain hindsight, with your case you can look this module https://www.drupal.org/project/token_eca_alter →

You can easy alter, extend exist token data.