AirBreather

I’ve bought a few of these before (no affiliation) https://www.amazon.com/dp/B0CCL7TJ48

Edit: this is a link to 1.5V rechargeable batteries, which I commented before OP’s edit acknowledging them.

Pretty much just now, they rebranded to Legcord

I can’t even imagine how my friend would take it.

OK, OK, time out. You haven’t tried talking with them about it? If you have as strong a mutual (platonic(ish?)) relationship with them as you say you do, then it should be able to survive a serious conversation about your shared future, especially if you emphasize that you want to try to keep them in your life in a major way like this.

That conversation will probably be hard, and I really can’t think of a solution that would feel perfect if I were in your shoes, but I would sure as hell rather have that conversation than the “I made a decision, and here is how you will be impacted” one, or the “I kept my life on hold because I was worried how you might react to talking about it” one.

I don’t know your personality or your friend’s personality, so I can’t promise that you will sort it all out without emotions running high, or what the ultimate outcome of such a conversation will be.

But jeez, bud, you’ve GOT to be able to have serious talks with people whom you trust and care about.

From the perspective of phylogenetics, if you believe that all trout species and all shark species should be called “fish”, then all mammals are also fish, including you.

I’m good until I run out, I guess.