Most green treated lumber is coated with chemicals to preserve how long they last, eventually… those break down and go into nearby soil. We used the same thing, we left some older green landscaping timbers and just lined them with thicker plastic and replaced the clay-like soil
I’ve been loving the Venu 3s, it has quite good hardware for the price point. Battery lasts 5-7 days, depending on my activities. I got a 20% off coupon by signing up for an app and doing 2-3 surveys, I can’t remember the name but it’s mentioned quite a few times in the Garmin subreddit (sorry I know…). Also get a couple different 18mm bands (I like nato style or a silicone band) and maybe a screen protector since it’s a raised bezel it’s prone to contacting more things than recessed glass.