I have a pacemaker. Can I safely wear/use this watch for everything else besides EKG??

For full and authoritative information please check the notes about product safety in the Apple Watch User Guide, Important safety information for Apple Watch - Apple Support

The "problem" for ECG if you have a pacemaker is not a matter of safety, but the action of the pacemaker device interferes with the ECG recording and makes it useless.

If you have any other compatibility concerns not explained in Apple's notes (above) you should consult your doctors who know the specific medical devices you are using.