I've yet to understand why the FT232RL gets used so much, FTDI have an FT230X which is smaller and cheaper and, AFAIK, hasn't been cloned
'fraid my experience with CH340g is not good ...
I have at least 1/2 dozen Arduino NANO with CH340g.
Using them as a user has been uneventful.
Tinkering with them is another story. So this may reflect the work at the design end may be more difficult. I think the 340g's TTL-load capability various a lot between chips (see below for why and see if I am wrong). Second issue: while the FT232RL datasheet said the 3.3v can support 50mA, I can't find out for sure how much the CH340g can support. So 3.3v load is also an issue.
The reason I think the 340g's TTL output load capability varies between chips is this:
I attempted to connect Arduino's TX and RX to use both the Arduino's internal USB and a blue tooth (and only one in used at a time). With the TX (send by Arduino's MCU), it is simple - one can have multiple listeners listening to the signal so the Bluetooth can just listen in on the signal. Two "talkers" to the RX (send to Arduino's MCU) is a different story - even only one active at a time. It means either connection must be able to pull the RX up or down while the internal chip may be at rest but connected.
I can make one configuration that works for all my UNO's and the FTDI NANO however I swap them. With them, I can just plug in my modified Bluetooth card and both the internal USB and BT can listen to the MCU and take turn talking to the MCU.
But, with the CH340g NANOs, I can't. I think I found one NANO that barely could. In essence, each NANO (each 340g) will need adjustments to resistors to allow both the internal and the BT to pull the RX to the right state.
My conclusion is that the TTL output load capability of the 340g varies too much. Besides that Bluetooth experiment, I have done no further work to confirm/repute that assumption so my conclusion may not be accurate. Experienced input welcomed.