Leenia, there are some guitars that would stand the tension. The smaller scale guitar can probably be tuned up a whole step without problems. Use a lighter gauge classical guitar string.

Also, if you tune up a half-step you would be in Bb. Tuning up a whole step to B might do serious damage to your full-sized guitar.

If the hymn is in D, why don't you just play chords in the key of D?

If you want to use the A fingering, you would have to capo up to do this. On a standard size guitar, you would capo on the fifth fret and play in A fingering for the key of D.

There is another solution. Open string tuning. You could use D,A,D,F#,A,D for the key of D (playing open strings). Here's the problem. To play G or A, you would have to barre
across all of the strings (which you don't like to do).

Since you don't like to barre, have you thought of using a steel-type guitar which is in an open chord and using a left-hand metal bar (as the steel or dobro players do)?

The other alternative is to have a specially made guitar to do what you want it to do (not too practical and expensive).

There are electric instruments that will transpose keys for you (another expensive
proposition). This can be done with an electronic attachment to your guitar.
(Also expensive).

Another idea, instead of tuning your guitar to standard pitch, experiment by tuning it a half or whole step and finding a key that would accommodate your fingering
in the left hand. If you tuned your standard sized guitar down to D,G,C,F,A,D you could play in the key of D by playing a fingered E chord. A fingered A chord would put you in the key of G. A fingered B7 would be an A7. If you did this, you would want to use a heavier gauge classical guitar string to accommodate the lower tension.

There is no easy solution to your problem.

Frank