Lifespans are just an estimate - you would need to speak to the company directly to confirm, but most say for those all in one seats, you can use it until the child outgrows it even if that surpasses the usual guidance, but you then shouldn't reuse it for another child. Whereas for example a baby seat or toddler seat might well be used by several children for a year or two each before reaching the expected usage limit. Personally I'm a bit sceptical of the idea of expiry dates for car seats anyway, certainly they aren't going to crumble to pieces at the 10 year mark, but in any case, you should be OK to keep using a seat throughout the groups that it has. The reason to discard them after a while is simply wear and tear - parts get lost, padding gets squished out of covers, covers get washed and may shrink, clips to keep the cover on get snapped, instructions and warnings printed on the seat may wear away. Misuse is more of an issue with older seats than material deterioration. And of course over 10+ years there have probably been increases in child seat safety.
WRT that BabyAuto seat I would want to check the size of the booster seat mode against other standalone booster seats and see if it's as big. If not you might be looking at getting a separate booster later on, but as said, these can be very budget friendly so would not worry overly about it for now, just to be aware it may not be as large as a standard booster seat. You do need top tether for that seat in both rear facing and forward facing mode, if you have top tether, it looks good. (I might go and recommend it to someone else actually who was looking for a top tether seat!) Also I would check the seat/harness size similar to the Joie Tilt just in case, as they list on their website/manuals that their 0-18kg seats are up to 3 years (whereas most manufacturers estimate 4 years). Whether that means their seats are shorter than average or they are just being conservative, I'm not sure :)