I've made a little progress. I just used all the original dts and added the include for the ipq5018-memory.dtsi and to my surprise i build without error, which it would not do before adding the extra dtsi. Still no wifi, and the switch is broke with this dts but I have a new error ...
[ 13.182361] Loading modules backported from Linux version v6.1.24-0-g0102425ac76b
[ 13.182400] Backport generated by backports.git v5.15.92-1-44-gd6ea70fafd36
[ 13.241293] xt_time: kernel timezone is -0000
[ 13.397830] PPP generic driver version 2.4.2
[ 13.399944] NET: Registered PF_PPPOX protocol family
[ 13.403081] PPTP driver version 0.8.5
[ 13.469918] ath11k c000000.wifi: ipq5018 hw1.0
[ 13.469962] ath11k c000000.wifi: FW memory mode: 0
[ 13.473771] remoteproc remoteproc1: powering up 4ab000.remoteproc_pd1
[ 13.535465] remoteproc remoteproc1: Booting fw image IPQ5018/q6_fw.mdt, size 1820
[ 13.535523] remoteproc remoteproc0: powering up cd00000.remoteproc
[ 13.549824] remoteproc remoteproc0: Booting fw image IPQ5018/q6_fw.mdt, size 1820
[ 13.668125] urngd: v1.0.2 started.
[ 15.919424] remoteproc remoteproc0: remote processor cd00000.remoteproc is now up
[ 15.931619] remoteproc remoteproc1: remote processor 4ab000.remoteproc_pd1 is now up
[ 15.964511] ath11k c000000.wifi: qmi fail to get qcom,m3-dump-addr, ignore m3 dump mem req
[ 15.967741] qcom-q6-mpd cd00000.remoteproc: fatal error received: err_smem_ver.2.1:
[ 15.967741] QC Image Version : QC_IMAGE_VERSION_STRING=WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1
[ 15.967741] Image Variant : IMAGE_VARIANT_STRING=5018.wlanfw2.map_spr_spr_evalQ
[ 15.967741] platform.c:717 Assertion 0 failed param0 :zero,param1 :zero,param2 :zero
[ 15.967741] Thread ID : 0x0000005b Thread name : wlan_platform Process ID : 0x00000001 Process name :wlan0
[ 15.967741]
[ 15.967741] Registers:
[ 15.967741] SP : 0x4c296f10
[ 15.967741] FP : 0x4c296f38
[ 15.967741] PC : 0xb023e830
[ 15.967741] SSR : 0x00000000
[ 15.967741] BADVA : 0x00000000
[ 15.967741] LR : 0xb022e260
[ 15.967741]
[ 15.967741] StackDump
[ 15.967741] from:0x4c296f10
[ 15.967741] to: 0x00000000:
[ 15.967741]
[ 16.022356] remoteproc remoteproc0: crash detected in cd00000.remoteproc: type fatal error
[ 16.044592] remoteproc remoteproc0: handling crash #1 in cd00000.remoteproc
[ 16.052877] remoteproc remoteproc0: recovering cd00000.remoteproc
[ 16.066411] remoteproc remoteproc0: stopped remote processor cd00000.remoteproc
[ 16.180734] remoteproc remoteproc0: remote processor cd00000.remoteproc is now up
[ 26.089770] ath11k c000000.wifi: failed to wait qmi memory request: -110
[ 26.089816] ath11k c000000.wifi: qmi failed to respond fw mem req: -110
which is related to this patch by @hzyitc -->Restart firmware after cold boot calibration for IPQ5018
This is not included because i am now using the ath11k-firmware from the wlan_ap repo that has the ipq5018-spruce firmware.
I am going to apply these patches to this version, fix the switch settings and use the correct m3-dump-addr hopefully this get me a little further.
In any case, I will not spend much more time on 5.15, I think i have what I need to move onto 6.6. hopefully i can catch up to @georgem83 and what he has done for the Linksys MX2000 Atlas 6 & MX5500 Atlas 6 Pro