Cheap upgrade (kind of upgrade anyway).

Ryzen 1700 to 2600X for main PC  £120 approx

Buy an Asus  x370-pro, approx £80 for my ESXi build, and add the 1700 from above upgrade.

All other parts needed I already own. Except maybe more storage needed for the ESXi build depending ultimately on what I decide to run on it.

Will definitely be running pfsense on it. And hosting a NAS server VM for outside access only, not my entire library that's on my main NAS. That's the plan so far anyway.