My experience of Home Automation is limited to 12 Sonoff or similar devices plus a Philips Hue hub etc. all controlled either by their respective app or by my 5 Amazon Echo devices.
I wanted to provide a non-verbal means of control using a redundant iPad, hence the purchase of the HEH but I have only been able to integrate the Philips Hue hub on to my HEH so far and realise that this is because the other devices are all working on WiFi rather that Zigbee or Z wave.
I stupidly didn't realise that the Hubitat Elevation did not cater for WiFi devices, but wonder if there is anyway forward (Tasmota?) or was my purchase of the Hubitat Elevation an error?
It does seem to me that Zigbee & Z Wave (as opposed to WiFi), devices are less readily available in Europe than they are in USA.
Any advice gratefully received
Have you tried Searching for Tasmota hear? I have 2 tplink plugs on wifi and HE.
Other option might be flashing them with new firmware to make them compatible, that might be a Google search
What are these other devices? Mentioning them buy name/model may lead others to help you find solutions to integrate them to HE
Sonoff devices can in general be flashed with Tasmota, with a few exceptions. Some are easier than others. Which models do you have?
If you can find your wifi device here in the supported section, it can be flashed with Tasmota and there is a driver for He. If it is not there, there’s still hope:)
Search isn't so bad. 
I don't know anything about Tasmota, but just put it in the search box and these were the first three hits.
What are these other devices?
The majority are Sonoff Basic or Sonoff plugs and I have some Maxcio Plugs which are similar to the Sonoff ones.
I also have some MOES switch modules that I have not installed until I decide which way to go.
Thanks markus and excuse my ignorance.
Do I understand that any items that I can flash to Tasmota could be controlled by the HEH?
I could try to flash some of the Sonoff devices, but less sure of others (Maxcio and MOES).
However, could you please point me to the broad procedures for using a driver on such a flashed device?
Thanks Mark. Could you please describe what you had to do to control the TP Link WiFi plugs?
Thanks
Would need model numbers to be sure, but most Maxcio Plugs and MOES Switches can be flashed with Tasmota. The Sonoff Basics can be flashed, so can the Sonoff Plugs. It might actually be easier to flash the non-Sonoffs if you have an RPi and use TuyaConvert (tons of youtube videos and tutorials for that one).
The first thread linked to by @SmartHomePrimer explains most of it, if not all. It has a bit of a learning curve, but what doesn't in DIY IoT?
I have tp-link plugs and switches and they work fine with HE. Just use the appropriate driver...
I agree with everyone here that your HE hub is going to be a great asset to your smart home. There are ways to integrate your existing equipment, and you can move forward with zigbee and zwave devices as your mesh grows. I also use non verbal triggers to control my smart home. I don't use a dashboard unless I'm not home. Our house interacts with us through motion sensors, contact sensors, and some cleaver DIY applications and modes. I LOVE HE. I have a smartthings hub connected for cloud apps and problematic devices. (just dusted it off recently) . I'm not a developer. I'm just a girl with some good ideas. As a commoner here, I would say that not using your HE hub will leave you pining for that "more" factor. Just sayin'
Thanks April.
I am grateful for all the answers and they have given me some encouragement and perhaps, some new viewpoints.
It seems that, if I buy an RPi, the Maxcio and MOES devices could be easier to flash wirelessly and therefore less trouble than the Sonoff devices .
I have not ventured into flashing Tasmota so far although the TTL UART module and cables is available
Additionally, would it be more sensible to replace the Sonoff WiFi basic devices with their Zigbee equivalents considering their low price, (although supplies may be drying up due to Corona)?
generally speaking, is it better to purchase the newest sonoff zigbee or tasmotize a regular one ?
btw, could be interesting:
I'll refer this to the community as I have no clue about Sonoff, but I'm a good googler! 
I'm still waiting for the Zigbee model to arrive, some initial reports say it works well with Xiaomi/Aqara sensors even. More time is needed to be sure. I will put 3 in my mesh as soon as they arrive. They work with HE without special drivers. @jchurch, all still well with yours?
Yeah they work fine, it it loads into HE using the existing native Nue driver so it must be running the same zigbee chipset as the Zemismart devices.
I second this as mine has been fine for months.
Here is a look at it.
You don't actually have to get a pi if you have a spare WiFi adapter as as you can run raspbian as a VM in and use the WiFi adapter to create the hotspot with Tuya convert.
Also Sonoff basics only take a couple of minutes to flash via TTL which I found was quicker and easier than going through the tuya convert process.
This can be complicated at times, the RPi is the easier route. If you're comfortable with Linux and VMs, this route is definitely a great one though.
Personally I flash everything TTL that is reasonably easy to open, but I use pogo-pins so I don't even have to solder. Maybe not for everyone, but it is a nice route, with that you're always certain to be able to recover and change firmware as long as you don't short the device.
Just received mine, they use the CC2530 chip, so unless their firmware would be oddly implemented this will work great with Xiaomi/Aqara. From what you're saying these work well, so I just have to say, nice little devices!
