@asmi - feel your pain. As we are somewhat still new to the world of FPGA devices, there is a high risk to bed down with a single vendor.
Being vendor-independent is a noble goal, but unfortunately it's not very practical especially when you deal with larger devices (say 50K+ LUTs) because you will be forced to use device-specific primitives to utilize the full potential of these devices. I use large-ish Xilinx devices as my main processing chip because I've learnt them well over years, and because they provide the best development resources on the market, including tons of free IPs which others charge big money for.
However here we are talking about smaller secondary utility devices, requirements for them are not very high, so here it should not be a big problem to switch between device families and vendors.
Often finding documentation issues (errors) as we dig deeper into the development cycle. Respectively we know that we will not get it right on the first try.
That is another reason why I prefer to stick with devices I worked with in the past - I've already invested time and money into figuring these things out, at the very least I know that regardless of the specifics of a board, I can be certain that I would at least be able to connect to and program device, and it will come online. So this way I simply retire a lot of risks related with getting some of the basics of connecting FPGA right, and so I reduce area where I can screw things up to peripheral connections. And these risks can often be retired by building a prototype extension module for some of my FPGA devboards (I always try to design a devboard for every major FPGA I plan to use in such a way as to cover as much of a ground as possible for porential peripheral connections).
So basically, as counterintuitive as it sounds, sticking to devices you are familiar with saves money.
HDI quotes are crazy high - for the WLCSP project, we had quotes of $1200-$1800 USD from China for 30 PCBs. Finally settled on one repeat PCB shop we have used with success who considered the HDI process as a norm and we paid ~ $600 for the HDI PCB lot. Much better but still quite high as compared to standard 4L pcb designs.
Can you please share that fab? I have few ideas about few breakout-style boards for a few of WLCSP-class devices, so I'm curious what would it cost to have it implemented.
You may want to review the QFN packaged Gowin devices with the hard M3 CPU (about 4800 LUTS). Their package can be deployed with JLCPCB specs which will be a huge cost reduction. Contact Edge Electronics (USA) for the best pricing but have the goods shipped directly from Asia to you in Canada. We did this from their HK warehouse of Gowin to avoid the Trump tariffs on Chinese goods. For our pending consumer space widgets, the QFN package is the wisest choice for us.
Thanks for the advice - I will take a look. Like I said, I prefer working with reasonable-pitch BGAs because they are much more space-efficient, which both saves money on PCB manufacturing and makes my final devices more compact. So if they have something that would suit my requirements - that would be great. Because using $20/pop MCU where a $0.5 would do (if only they can be actually procured) feels very wrong to me, but sometimes you've gotta do what you've gotta do...