LoRa link from my basement to my flat

I want to put some sensors in my basement, where I have no network and no mains access. The plan was one or two battery-powered ESP32s transmitting data regularly up to my flat via LoRa, with the option of a mains-powered relay or hop near the basement unit (though not inside it) if that turned out to be necessary. The basement is five floors away, so I wasn't sure it would work, but after watching a couple of Andreas Spiess videos I thought it could.

I had no experience with LoRa or antennas, and I was very surprised by the price of the ESP devices sold "for LoRa", Heltec and all: the boards I'd seen were four to five times the price of their non-LoRa counterparts. I decided to just order a few and pay a bit extra for quality so I'd have a baseline, and cheap out later. I got two Heltec WiFi LoRa 32 V4 boards, and they also had a LilyGO T-Deck with LoRa at 868 MHz on sale, which I bought to add to my collection of cool boards I never use. (The actual T-Deck I bought is here.)

I'll admit I still have no idea how all of this works, or why you can't just get a breakout board. But I found ESPHome's packet transport component, which is absolutely amazing, and I can't believe how complete ESPHome is.

I'm happy to report that I can report back from the basement all the way up to the fourth floor. This is absolutely insane and I am so stoked. It turns out I don't understand radio waves, because I don't understand how this can work: there's no way the signal is travelling directly, so it must all be reflections. I do get 5G in the basement, so I shouldn't be that surprised, but the phone's antenna is 200 mW to 600 mW rather than LoRa's 25 mW. I like being pleasantly surprised, so I'll take it.