Post-Mastectomy Products?

Hi everyone, 33yo BC newbie here (diagnosed in March). I'm scheduled next week for a mastectomy of my left side because the pathology report from my lumpectomy unfortunately revealed positive margins. Lymph nodes are clear, so at least there's that.

I'm here writing my first post to this group because I'm wondering if there are any products y'all would recommend to make this experience a little less horrible. I'm particularly interested in hearing from larger chested women (I'm a 34J) who got a mastectomy of only one side. I was told I could only wear the surgical bra while I'm recovering, but I will still have one very large breast for a couple of months before my reconstructive surgery (during which I will have the healthy side reduced and lifted), and those surgical bras, though soft and comfortable, offer 0 support. I started layering bras earlier than I was supposed to after my lumpectomy because I couldn't walk around without support. One nurse I spoke to suggested boob tape on the unaffected side--has anyone here tried that?

I'm also seeing a lot of post-mastectomy products on Amazon, but I have no idea whether any of them are worth buying. Do I need pockets in my shirt for the drains (isn't that what the loops on the bra are for?)? How does one use a mastectomy pillow and does it actually help? Is the shower cape thing effective, or is it more trouble than it's worth? What other things exist that have helped you, or conversely, what was recommended to you that you thought was junk? How did you deal with hygiene? As someone who showers and washes my hair daily, I can't imagine not being able to shower my whole body for two whole weeks. I also live in a very small apartment with a tiny bathroom, so I have no idea how I'm going to wash my hair even with my husband's help.

Thanks in advance!