If you're a fan of the Model M then you must know about Unicomp[1]
ergodox that usually put out a split ergonomic keyboard have recently released a cut down keyboard called the Planck that might interest you[2]. But to go from a gigantic beast of a keyboard to such a wee thing might be daunting.
The /r/mechanicalkeyboards dwellers might be able to help you out as well[3] as well as the mechanicalkeyboards website[4]
FWIW I happily used a Filco Majestouch for years before switching to an 'ergonomic' keyboard (ergodox). The Microsoft Ergo Sculpt is really good for me as well, I still use it on my secondary desktop.
I actually asked in /r/MechanicalKeyboards, but they didn't help much, just pointed me to Unicomp but that's not what I'm looking for as it's basically the same size as the Model M. It looks like Unicomp will be releasing a "Spacesaver" Tenkeyless model in the upcoming weeks [1], that might be an option.
The Filco Majestouch 2 Ninja TKL [2] is one of my top candidates right now, or a Ducky One 2 TKL [3] variation. I actually tried to get both in the past weeks: the Filco couldn't get shipped because of COVID-19; and the Ducky One 2 ran out of stock (the European market problem I was mentioning before). Very frustrating.
About ergonomic keyboards I don't want to go through the pain of relearning how to type. I have been typing on the Model M for 25 years now and my muscle memory is deeply engrained, I want a layout that is as similar as possible (so 80% Tenkeyless).
The Planck seems unnecessarily small to me. I'm not moving my keyboard so the absolute smallest size is not a requirement, I just want to get rid of the numpad to have the mouse closer.
Instead of Ducky One 2, I would look into either Varmilo or Leopold. Similar design, better quality and in the case of Leopold its very understated, no RGB and game-ry branding.
I have heard good things about both Leopold and Varmilo, but they are even harder to come by than the options I mentioned. I have to compromise for a keyboard I can buy in the EU (but with an US layout).
ergodox that usually put out a split ergonomic keyboard have recently released a cut down keyboard called the Planck that might interest you[2]. But to go from a gigantic beast of a keyboard to such a wee thing might be daunting.
The /r/mechanicalkeyboards dwellers might be able to help you out as well[3] as well as the mechanicalkeyboards website[4]
FWIW I happily used a Filco Majestouch for years before switching to an 'ergonomic' keyboard (ergodox). The Microsoft Ergo Sculpt is really good for me as well, I still use it on my secondary desktop.
1. https://www.pckeyboard.com/
2. https://ergodox-ez.com/pages/planck
3. https://www.reddit.com/r/MechanicalKeyboards/
4. https://mechanicalkeyboards.com/