Backdrop might be a solution. But have been working with Drupal for a bit over 25 years from D4 and migrated sites via D6 to D7. Just love D7 and made for my customers several custom modules. One of the last was an integration of Bitcoin payments per product. For that I used the cart modules which I heavily adapted to be able to have payments via a BTCpay server for products. To migrate to D8-D10 would basically mean I have to rewrite the whole site and several modules which are available in D7 but not in D10. It is just to much work which my customers do not want to pay for and I have basically to drop all knowledge on D7 and start new to learn D10..
Even going to backdrop will take time but to be honest have not (yet) went deep into it. I just feel Drupal just does not care anymore and the community is shrinking. I think Drupal will eventually disappear completely and only used by big companies who have the money to invest in this and because some people have experience with it.
I do have some small sites working in D10 and as long no special needs are needed, it works okay.
I have given up on trying to get into the mechanics of D8-D10, just have not the energy and time to start all over again. For me it means that once D7 is not maintainable anymore, I will tell my customers to go somewhere else and close the shop. Am just not able to migrate about 60 sites to D10 since it is missing some for me essential modules and have to rewrite several specialized custom modules. From the (shrinking) community I do not expect much anymore since a lot of modules in D7 will not migrate to D10.
It is just a shame Drupal, which in my eyes had much potential is just fading away and probably nobody will know about it anymore in a decade (apart from the old timers).
Have seen a lot of things come and go in the past and am afraid Drupal will be from the past very soon if this development continues.
I have been using Drupal for 20 years and created several specialized modules. With the emerge of D8/9/10 I ran into several problems:
Several modules I use are not available (yet) and basically had to find replacement or write the module. Also had to reprogram most of my custom code to be able to work in D8+ Which is simply not doable, not only because of some learning curve needed to understand all hooks in D8+ and be able to use them, but also just time which is not paid and will be many many hours. (that apart from the migration problems.) I migrated from D4 to D6 and to D7 and that was reasonable simple. But with D8 I basically had to start all over again to lern the internals of Druapl.
For now I just stay with D7.
Might be I am just getting to old for this shit and sticking in the past, not flexible anymore. I just wished it was easier to migrate. Thing is that with a lot of other platforms you can migrate without rewriting custom code and often not missing modules. Just hope D8 will be there for a while longer.