My thoughts is to keep the TD 10/22 relatively simple but with premium parts. No plans to add fancy optics, lights, bipods etc. Maybe a cheap red dot just to get them started. I can't take out my oldest offspring shooting until next Summer, which is when he is permitted to come with me to the outdoor range. Hopefully next month will produce some great sales.
I plan on going the TacSol Xring now. It has all the bell and whistles anyone could want. Lightweight, fluting, threaded, steel shank, accurate and has iron sights. I did consider the charger route with the reason why your kids enjoy them. The weight savings and less leveraged weight at the end of the barrel. Too much uncertainty with "pistols" though right now depending on how the ATF responds to "Q" and its possible implications for other "pistols". I did weigh that option heavily initially.
When I think heirloom, its not necessarily the classic wood stocked blued finish heirloom I was thinking, but more so a reliable, durable piece that can be passed down because they work well and brings back memories for them. It is for them to enjoy and hopefully they can share that joy with their kids 1 day. I know most people think that classic hunting rifle format when heirloom comes to mind. I feel like the appreciation for nice wood on rifles is fading. I'll admit I am not 1 to be able to fully appreciate the beauty of a nice wood finish on a rifle. I like seeing them, but wouldn't want one. The build will be essentially a custom 10/22 where it won't need anything changed. The only Ruger about it will be the BX-25 I intend to get once it becomes available and maybe a bolt with upgraded hardened parts. I wouldn't want to go hunting now with a wood stock, even though I know its fine, I prefer the weather/ding resistant polymer options out there.
While I did consider getting a bolt gun for them, I decided against it because I feel like they will enjoy the 10/22 more. Cost of this 10/22 will already be upwards of $600 per rifle. And I am building two. However, A Tikka T1x in 17hmr is on my wishlist to teach the kids on a bolt action platform though. That will eventually replace my Savage 93R17 Heavy barrel threaded which will probably end up in their hands 1 day for a plinker for them.