Hello,is there openwrt support for this GPL'ed device https://www.tp-link.com/us/deco-mesh-wifi/product-family/deco-xe5300/ espesially v1 ?
It's not GPL'ed. TP-Link will - at best - offer a tarball with an ancient SDK and lots of binary blobs which gets you a functional image. But 99% of the time, lots of essential code is missing because it's closed source.
If you want to know if it stands a chance at being ported, find out the internals, and someone who might do the porting if they are provided with a device.
This is basically a support request, the 'For developers' section is intended for actual porting efforts.
…and a very casual look suggests ipq50xx, which no one has been working on so far (chances are low, very low).
It's ever worse, it's Broadcom, unless different versions use different hw.