Description of the need Some tokens are missing from Backdrop and D7 core. This issue is addressed here https://www.drupal.org/project/token/issues/691078 and is considered major. Maybe all the needed tokens are already included in the Entity Tokens module which is now available in Backdrop contrib.
As an example I'll present here some tokens available in D8/D9 about forums which are missing from Backdrop core. Though, Entity Tokens provides availability of most of them if not all. We just need to check if there is anything not covered by the Entity Tokens module and if this module should be part of the core.
Please see in the attached photo what taxonomy tokens Drupal 9 now offers

Recent comments
Thanks Alejandro. That was the clues I needed.
Ubercart - Programmatically add product to cart and straight to Checkout
Have you tried uc_cart_add_item()? You need to provide the nid of the product. Then you can use backdrop_goto('cart/checkout'); to send the user to the checkout screen. uc_cart_add_item...
Ubercart - Programmatically add product to cart and straight to Checkout
No problem, let's see how it evolves. I'd be happy to provide a suggested version if i could. I will keep that in mind and try learn this hook chain hopefully very soon. I will...
File hashing uploads made through TinyMCE