I was disappointed as well, seeing far less than 1000 Youyota tablets ordered. Well, I believe there are a couple of minor factors, which may improve the situation for the Livermorium phone:
- Leave the campaign open for 4 to 6 weeks. Because with the short 2 week campaign for the Youyota tablets, new preorders almost dropped to 0 after the campaign's official end, as most people were not aware one could still order after that. Still there obviously was some remaining demand (questions on TMO, a friend who was on holiday etc.), but presumably most people just shyed away, thinking "Oh, I am too late!".
- Restrict engineering efforts to essential changes, e.g. Keyboard, replaceable battery. Seriously consider things like a multicolor LED only, if they seem to be easy, and drop any of these extra features immediately, if it turns out to be harder (in terms of engineering efforts / risks or parts / production costs) than expected.
- Restrict software engineering to a working, open boot loader and LineageOS / SailfishOS to simply run well. Not all hardware features have to be supported from the start, for such a small series device you can / may have to rely on independent developers ("the community") to implement minor features.
- Explicitly ask people (e.g. here on TMO) to "spread the word" in the internet, when the preorder campaign starts (but not before being able to name a specific opening date for the campaign).
- Set your funding goal accordingly, i.e. at least for ~ 1000 units.
- Most people do understand well, that this is an unique, small series device, which involves high costs. So do not try make it competitive in price to comparable devices (plus < $100 for the keyboard): An extra of $100 to $200 for just being a special, small series phone is somewhat expected (but sure will be a reason to complain for some ;\ )
- Do have the Youyota tablet and the MotoG keyboard delivered, before the Livermorium campaign starts, so more people will trust you(r experience, capabilities etc.).

Look, the development of the Pyra (on Wikipedia) bears some similarities, albeit at a far slower development speed, as they are engineering everything from the ground up (and mostly produce in Europe). It has attracted slightly more than 1000 preorders, despite its high price, and is finally close to delivery (and they have proven this effort to be economically viable by saving / managing to produce the Pandora).

All in all such an enterprise has to be economically viable, otherwise it will fail, unfortunately.
And I would not count on a significant market after an IGG campaign in the first place; you may try that with surplus Youyota tablets, but that needs infrastructure (web shop, distribution, financial transactions etc.).

P.S.: I would expect 1000 to 2000 preorderd Livermorium phones with SailfishOS to be surely attainable, 2500 / 3000 if you / we are lucky.

Edit: You may also consider a keyboard-less variant of it (assuming this is a really easy change) to gain a few more preorders.

BTW, above statements do not imply any criticism of how you proceeded with the Youyota tablet; that was a different situation, as the design was almost fixed, while speed was paramount.