Following up on my own post above so others have a sense of the current connection situation; we ended up keeping the 9:35am SCL-PUQ flight and we made it without any problems. We certainly had to hustle a bit, but I was amazed by how smooth the int'l-domestic connection process was: cabin crew opened the door to disembark our int'l flight at 8:10am and by 9:10am, we had stepped onto the plane for our flight to PUQ. The full rundown is below, just in case anyone is interested in how long the various steps took. Of course, YMMV, but 1hr45m was enough to make our connection, even with a slightly late (~10 mins late) gate arrival.

As we were sitting in J, we were one of the first off the plane, and it didn't seem like many other flights had arrived around that time (~8am), so we walked right up to an immigration officer without any wait. 10 minutes after stepping off the plane: cleared immigration.

Our checked bag came off the belt very quickly - maybe 5 minutes of waiting after clearing immigration (side note: we flew LATAM several more times during our time in Chile and I was very impressed by how quickly they got the bags off on all of our flights). We had already filled out the SAG's online customs declaration, which makes the process quite smooth. If you have nothing to declare, the form shows a green check mark that you show to officials who quickly waive you through. My partner did have some items to declare (some food items that we were taking on the trail for our Patagonia hike), so she had the "red" check mark and got sent over to a customs officer. After explaining that it was just a few snacks, she was waived on her way without any search of the bag.

After proceeding through customs, there's a transfer bag drop to recheck bags for domestic flights. Only one agent was working the desk, so we had to wait a few minutes before we could recheck the bags (there also appeared to an automated belt where you could scan a boarding pass to self-tag your bag, but it was broken when we were there). 30 minutes after stepping off the plane: cleared immigration, cleared customs, rechecked bag.

Next comes the walk from the new international terminal back to the domestic terminal, which took a little over 5 minutes (at a very brisk walking pace). Then clearing security at the domestic terminal, which had a short line and was a very relaxed experience compared to the usual TSA adventure in the US. 50 minutes after stepping off the plane: cleared immigration and customs, rechecked bag, cleared domestic terminal security.

Our flight to PUQ was boarding from a far-flung gate in the corner of the terminal, so we had more walking to do, but 60 minutes after stepping off our inbound international flight, we had completed everything and were pleasantly onboard on domestic flight. All in all, a very smooth and well organized connection process at SCL.