I agree. What you say about avihimsā is an appropriate way to regards the environment from the point of view of the Dhamma.
The efficacy of the Dhamma is measured in terms of internal mental purity, with respect to the objective ideal of nibbana.
The efficacy of environmentalism is measured in external environmental purity, with respect to a subjective ideal of a utopian environment.
Avihimsā contributes directly to internal mental purity.
"Having understood name-and-form, which is a product of prolificity,
And which is the root of all malady within and without,
He is released from bondage to the root of all maladies,
That Such-like-one is truly known as 'the one who has understood'." (Snp 3.6)
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)