Long story short: nowadays 65W-capable USB C powerbanks make more sense in my opinion, than multiple Thinkpad batteries. And they work with all laptops.
Yep just like the S versions they have a double battery. This is great because the total can get close to 100Wh (when using the 72Wh external) but hot-swapping requires an internal battery in good shape which is not so easy to come by. From Lenovo they can be very expensive or not available. From third parties you're always gambling that those batteries will play nice with the proprietary Thinkpad EC.
I bought both (3rd-party) batteries for a T440S, and the internal would suddenly show up as 0% every couple of weeks, and had to be "reset" by opening the base, unplugging and plugging it in..in the end I just put the original internal back; the external has been amazing instead, and it does basically all of the work since it's the 72Wh version. Fun fact: these laptops work perfectly with only one of the batteries attached.
I've found that L and E series seemingly mirror the T line but with a couple of years of delay, so overall with time it gets worse repairability wise, but gets better with things like 16:10 screen aspect ratio.
I haven't researched the 2024 T series, is it noteworthy other than having some models with ram slots? Feels like some hype is going on. In any case, expect ~2026 L,E series to have similarly constructed models.