Thanks for the welcome - I actually started with rtl_433 and trying to get it working with weewx before coming across Andrew's qruqsp project and realised that a lot of the hard work had been done and I wouldn't need to 'fudge' things to make them work, though I've still had to poke under the bonnet of qruqsp a little here.
My remit was to get data usable as listed in my original posting. So far, (as of 31/12/20) I've gotten everything working (prior to doing more with the greenhouse):
First hurdle - receiving the 'Bresser 5 in 1' on 868Mhz - while qruqsp is setup to receive devices on 433Mhz, it's simply a case of telling the SDR to listen on 868Mhz by editing the script at ~/ciniki/sites/qruqsp.local/site/qruqsp-mods/43392/scripts - and part was down you'll see all of the initialisation for the SDR - simply add to the second set of strings: -f 868M (and -s 1024k to alter the sample rate) and - woop woop - the SDR is receiving at 868Mhz and happily found the 5 in 1.
Simply a matter of setup the weather station once discovered and away we go. (I have a spare 5 in 1 here to trial with during my vacation.)
Second hurdle - I'm going to return to this once back at school as I've got more work to do inside the greenhouse re solar charging for fans, lighting, etc as the greenhouse is off-grid and I want some form of fan temperature control so the internal temperature can be regulated.
Fortunately 'aliexpress' and 'Bang-good', etc, all sell pre-made boards to achieve this so all I really need is a 868Mhz temp sensor to send data to the Pi so it can be incorporated into the system to enable remote monitoring.
I'll be returning to this part soon once I've built a control panel, etc and got solar charging working again using a premade controller.
Third and final hurdle for now - BME280 sensor done today (31/12/20) as the interconnects arrived so I soldered the header onto the board, attached it to the Pi and nothing found under i2c.
Think think think - got to be a simple answer to this - and there was - go into 'raspi-config' and enable the i2c bus in the software. Rebooted and there was the BME280 sensor at the right address (0x76) ready to be configured and activated. Barometer, etc, all working fine there.
APRS can wait as I simply want the get the system installed in school (it's all encased in its own acrylic housing) and get it looking at my school network and sending data to Weather Underground (which it's doing now though all my temperatures are internal readings).
I did start this project in September but only recently found time during my vacation (and the UK pandemic lockdown time) to return to it but I'm so glad I did. My original trials in weewx I felt very messy (though I will return to look at it sometime) and I like the displays that qruqsp supply that we can use on some of the display screens in school that are to be Raspberry Pi powered from Spring. (My next project!)
It will be great to see if Andrew adds more to it - I'd love the see the Lightening sensor added and maybe even a soil hygrometer, etc.