Hi,

If you tried to avoid the recomputation of various columns in the model "product.product", you should consider applying changes directly in Postgres. However this approach:

1. Is hard. You should modify not a single database table but a few related ones. The system of attribute values tables is quite complex in Odoo

2. Is risk-prone. Various recomputation and inverse triggers do quite an important job. You should take it into account since otherwise data will be inconsistent and will lead to errors.

So, in general, the "deletion and re-creation of product variants" you mentioned in your question is what is actually needed for such cases. Simple replacement of an attribute value is actually neither simple (needs to make SQL updates) nor good (might have severe consequences for data consistency).

If you decided to follow a common Odoo approach with all its subfunctions, please also consider this module - https://apps.odoo.com/apps/modules/16.0/product_management/. It is designed exactly to make mass template updates, including adding and removing attribute values (with variants recreation)