The most promising approach I've seen to integrating Linear Types in an effective way. They've also thought about how to do borrowing, and other things.
Being a research language, some academic papers have been written about aspects of the language.
(2016) Combining Effects and Coeffects via Grading
(2019) Quantitative Program Reasoning with Graded Modal Types
(2021) Deriving Distributive Laws for Graded Linear Types
(2021) Graded Modal Dependent Type Theory
(2021) Resourceful Program Synthesis from Graded Linear Types
(2021) Linear Exponentials as Graded Modal Types
(2022) Linearity and Uniqueness; An Entente Cordiale
(2024) Functional Ownership through Fractional Uniqueness