That's still a vague set of parameters. But if kind of endurance and maybe aero, I can recommend my ltk268, because it's definitely aero, but the geometry is more relaxed than the vb268 and many of the Chinese aero frames.
Either way, I'd say make sure you go with a frame that takes at least 32C. Potentially, if you want something that is really on the endurance side, a frame that takes up to 38C like the new long teng 301 may make sense. With such a wide fork you got to have more drag, but the trade off could be worth it. Also the 301 is much more recent than the 268. They're both cheap, which I think is largely due to the fact that you will not find any marketing, discount code, kick back and so on. From experience, their low price point doesn't mean they're poor quality, quite the contrary.
Check out geometry bikes geek website, I'd say don't buy anything that's more aggressive than the 268 / 301 (more aggressive means longer reach and lower stack).
Don't get a gravel bike based on the use cases you listed. Don't get something too aggressive. Do get at least 32C clearance.
I'd also say, get wide rims, like Peter s 34mm wide rims (from carbon speed Xiamen), he's on the forum. With these, you can get 30C and stick to the 105 rule. I have a 32C on this rim measuring 33.5mm and it's awesome for comfort (and grip).
