https://downloads.openwrt.org/snapshots/targets/ipq806x/chromium/
Regular snapshot builds are done every few days. Latest is from this morning 6th of May. Some packages are dependent on the kernel / build version so if you get warnings / errors then you should update to the latest snapshot first.
You can use 'attended sysupgrade' to update to the latest snapshot which will include all the currently installed packages in your upgrade and makes things a lot easier.
The warnings / errors should disappear when the next stable OpenWrt release is done.