Would this BLE adaptor allow me to connect to a Pixl.js over a longer range, or would the device on the other end also need a proper antenna? I'm guessing the latter, but just wanted to double-check.
Yes, the USB Bluetooth adaptor would definitely help - obviously you get best performance if both devices have an external antenna, but even if just one has an antenna it's a marked improvement.
The 'long range' in name probably does not mean it supports BT 5.0 125kbs or 500kbps long range Coded PHY modes that 52840 chip can do? (as described e.g. here https://blog.nordicsemi.com/getconnected/tested-by-nordic-bluetooth-long-range). For a moment I was hoping it is dongle just for that.
And BTW the product link https://www.feasycom.com/product/show-384.html in shop page goes to 404 , is it this one https://www.feasycom.com/product-100m-usb-bluetooth-dongle.html ?
Thanks - just updated the link.
Yes, it's a standard Bluetooth Low Energy 4.2 dongle - no fancy 5.0 features like long range (not that those are currently supported by Espruino devices anyway).
It's what I use on my desktop here (and for flashing Bangles) so I'm reasonably confident in it. There's a very noticeable improvement in range over the standard USB dongles (and the one usually built into laptops).
It's been pretty difficult to get hold of Bluetooth LE adaptors that have decent aerials on them, so I have now started stocking some in the Espruino store:
I've been using one for a few weeks now and I'm noticing significantly higher range. They work great with Windows and Linux.
I've also got a batch of MDBT42Q Breakout boards made with a u.FL socket for an antenna, and these seem to really help with range as well. I'm seeing between 5-20 dBm increase in RSSI values when scanning for advertisements from the board.