My family needs a new router to replace the old (though not old enough that it should be dying) netgear router that is slowly dying. I want to do something with good foss firmware like opnsense or openwrt. I was thinking that the BananaPi options look good, but had some concerns. I would like to install the firmware myself, rather than trust that the manufacturer didn't modify it in any way. I don't know if the pre-made openwrt bananapi routers can be flashed with custom firmware easily. Also I need something with wifi (ideally wifi 6 or better), though would be willing to consider a separate WAP. VLANs would be nice too, but I could live without them. Have any of you done this? What has your experience been, both with install and long term? Is there anything I should look out for that I might not think of? What resources can I use to find out more about this?

Edit: This is the one I'm looking at. Sorry for linking to Amazon but I used FF's remove tracking from URL feature. https://www.amazon.com/youyeetoo-BPI-R3-Development-MediaTek-Support/dp/B0BLVF9697/ref=cm_cr_arp_d_product_top?ie=UTF8