The temperature does not rise above reasonable limits, and I doubt it will in the future, so there is no need to worry about thermal throttling.
ASUS doesn't like you opening up their routers, and they make that clear when they put those warning stickers over the screws, but at least in the US, you should be protected from such tampering, well, you should. The process is pretty simple. You need to remove four screws, then use a pry tool to pop the bottom off.
asus-rt-axe7800-teardown
Then we see some heat spreaders on both sides of the georgia telegram data PCB that also need to be removed, and that also means disconnecting the antenna connectors. Nothing too complicated, since there is no gel or glue or whatever you call it. Then we see the main components.
ASUS RT-AXE7800 ASUS RT-AX86U Pro ASUS RT-AX88U Pro ASUS ROG Rapture GT-AX6000
CPU Quad-core 1.7 GHz Broadcom BCM6756KFEBG Quad-core 2.0GHz Broadcom BCM4912 Quad-core 2.0GHz Broadcom BCM4912 Quad-core 2.0GHz Broadcom BCM4912
RAM 512 MB Samsung SEC201 K4A4G165WF 1 GB 2X Samsung SEC 234 K4A4G165WF 1 GB 2x Samsung SEC 310 K4A4G16 1 GB 2X 512 MB SKHynix H5AN4G6NBJR
Storage 256 MB MXIC MX30LF2G28AD-TI 256 MB MXIC MX30LF2G28AD-TI 256 MB MXIC MX30LF2G189C-TI 512 MB MXIC MX30LF2G28AD-TI
Switch Broadcom BCM53134SKFBG Broadcom B50212EB1KMLG PHY MaxLinear MXL SLNW8 2.5GbE Ethernet PHY Broadcom BCM50991E
Radio 5 GHz Broadcom BCM6715KFBG 802.11anacax 4×4:4 Broadcom BCM6715KFBG 802.11anacax 4×4:4 Broadcom BCM6715KFBG 802.11anacax 4×4:4 Broadcom BCM6715KFBG 802.11anacax 4×4:4.