The DR1801 is not supported by the OpenGD77 firmware
Supported Baofeng radios are the now discontinued DM-1801 and RD-5R.
And the DM-1701 which is still in production
All other radios use different chipsets
DM-1701 is by far the cheapest, but the screen currently has some clipping because the plastic overlaps a few mm over the edge of the display.
Also the DM-1701 does not have a GPS option, and its non-trivial to attemp to retro fit a GPS to this radio.
The next cheapest option used to be the Retevis RT-3S, which is a rebranded TYT MD-UV380, but these now seem more expensive than buying the UV380
UV380 now seems to be sold as the UV380Plus, possibly becuase they put a better GPS receiver in it, there don't seem to be any other hardware differences
UV390 is the waterproof UV380
Its possible to retro-fit a GPS to the UV380 becuase it has space for a GPS receiver and space for its antenna.
You need to look around and find the prices for all of these in your locality