Thanks for pointing out band 40. Apparently it's just used in China, but it is supported on the iPhone 13.
Band 30 is a no-go because the downlink is at 2350 to 2360 MHz, which is not a ham band. The ham band is split because of satellite radio. It's 2300 to 2310 and 2390 to 2450 MHz.
Band38 is the one most 2.4 GHz WiFi-covering half-duplex SDR can handle, at least if modified/adjusted with a local oscillator quartz suitable for LTE. It's an ugly fraction to synthesize with a fractional PLL to LTE-specs of local-oscillator-quality.
Yeah, it's not ham, but low power levels and RF-shielding-cages should suffice to keep radiated emissions far below interfering levels.
It's also surprisingly well supported, at least on non-US handsets, from when I researched it a bit a few months before the first wave hit and blocked collaborative hardware hacking.
The 13cm band is a bit of a mess globally.
Here in Finland it's still full 2300-2450MHz. But in 2300-2320MHz it is shared with lightly licenced "provate LTE".
Hop over to Sweden and it's 2400-2450MHz only with a powerlimit under a watt.
And im USA it's that pumctured mess, isn't there also AT&T running Band30 FDD-LTE? Years back when I was searching for LTE phones with Band30 for hamLTE use I only found AT&T carrier locked stuff from USA.
North americans also have 902-928MHz 33cm band, but that lacks the paired spectrum above it, so FDD-LTE or GSM are not possible. And I don't think there's a widely supported TDD-LTE spec for it.