That’s a beast! Post a video of it in action!
It’s a great learning exercise but challenging to get right and ensure your deliverability and basically impossible from a residential-grade IP address (if you have a business class static IP at home you could pull it off).
I ran an email server for decades but gave in and pay to host my email now.
If google decides you’re a bad guy it’s such a pain to crawl back from that and I prefer my email to just work.
Which features of Lightroom are important to you? The editing capabilities? Organizational capabilities? Cloud sync?
I ran on a Celeron J1900 for a while and for basic home services it was great.
I didn’t do any emulation or media transcoding so I can’t comment there. But I did run vpn / nas / web host kinda stuff.