Tricky, tricky. I happen to have talked to them NXP Wi-Fi people lately as we are an NXP partner and do use them former Marvell chips in some of our products as well. While much of such discussion is under NDA I guess I can share that NXP starting with their October 2020 i.MX Linux BSP release includes validated mwifiex Wi-Fi driver/firmware now as well. While they started with 88W8987 support they plan to add more over time. Just before X-mas they released the next version which added 88w8997 support as well. Their latest release notes may be found here. I would have more detailed Wi-Fi release notes which I believe are not NDA restricted and are supposed to be publicly posted as well. However, I could not quite find them anywhere on NXP's website as of yet and I don't believe I can upload PDFs to this forum. PM me and I can send them along.
Anyway, one idea could now be to integrate those drivers/firmware for use with OpenWrt on them WRT routers as NXP will regularly officially validate and update those (e.g. for their quarterly i.MX BSP releases).
As mainline Linux support is important for us as well we will keep bugging NXP about this and I will mention OpenWrt in our next sync call with them as well. Let's see...